TSQLFile.cxx

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// @(#)root/sql:$Id: 6f6608219c30ddefdf8e25d7cf170d5e69704cd3 $
// Author: Sergey Linev  20/11/2005

/*************************************************************************
 * Copyright (C) 1995-2005, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

/**
\class TSQLFile
\ingroup IO

Access an SQL db via the TFile interface.

The main motivation for the TSQLFile development is to have
"transparent" access to SQL data base via standard TFile interface.
The main approach that each class (but not each object) has one or two tables
with names like $(CLASSNAME)_ver$(VERSION) and $(CLASSNAME)_raw$(VERSION)
For example: TAxis_ver8 or TList_raw5
Second kind of tables appears, when some of class members can not be converted to
normalized form or when class has custom streamer.
For instance, for TH1 class two tables are required: TH1_ver4 and TH1_raw4
Most of memebers are stored in TH1_ver4 table columnwise, and only memeber:
    Double_t*  fBuffer;  //[fBufferSize]
can not be represented as column while size of array is not known apriory.
Therefore, fBuffer will be written as list of values in TH1_raw4 table.
All objects, stored in the DB, will be registered in table "ObjectsTable".
In this there are following columns:
| Name | Description |
|------|-------------|
| "key:id"  | key identifier to which belong object |
| "obj:id"  | object identifier |
| "Class"   | object class name |
| "Version" | object class version |

 Data in each "ObjectsTable" row uniqly identify, in which table
 and which column object is stored.

In normal situation all class data should be sorted columnwise.
Up to now following member are supported:
  -# Basic data types. Here is everything clear. Column SQL type will be as much as possible
    close to the original type of value.
  -# Fixed array of basic data types. In this case n columns like fArr[0],
    fArr[1] and so on will be created.
    If there is multidimensional array, names will be fArr2[1][2][1] and so on
  -# Parent class. In this case version of parent class is stored and
    data of parent class will be stored with the same obj:id in corrspondent table.
    There is a special case, when parent store nothing (this is for instance TQObject).
    In that case just -1 is written to avoid any extra checks if table exist or not.
  -# Object as data member. In that case object is saved in normal way to data base and column
    will contain id of this object.
  -# Pointer on object. Same as before. In case if object was already stored, just its id
    will be placed in the column. For NULL pointer 0 is used.
  -# TString. Now column with limited width like VARCAHR(255) in MySQL is used.
    Later this will be improved to support maximum possible strings
  -# Anything else. Data will be converted to raw format and saved in _streamer_ table.
    Each row supplied with obj:id and row:id, where row:id indicates
    data, corresponding to this particular data member, and column
    will contain this raw:id

All conversion to SQL statements are done with help of TSQLStructure class.
This is special hierarchical structure wich internally is very similar
to XML structures. TBufferSQL2 creates these structures, when object
data is streamed by ROOT and only afterwards all SQL statements will be produced
and applied all together.
When data is reading, TBufferSQL2 will produce requests to database
during unstreaming of object data.
Optionally (default this options on) name of column includes
suffix which indicates type of column. For instance:
| Name | Description |
|------|-------------|
|  *:parent  | parent class, column contain class version |
|  *:object  | other object, column contain object id |
|  *:rawdata | raw data, column contains id of raw data from _streamer_ table |
|  *:Int_t   | column with integer value |

Use TSQLFile::SetUseSuffixes(kFALSE) to disable suffixes usage.
This and several other options can be changed only when
TSQLFile created with options "CREATE" or "RECREATE" and only before
first write operation. These options are:
| Name | Description |
|------|-------------|
| SetUseSuffixes() | suffix usage in column names (default - on) |
| SetArrayLimit()  | defines maximum array size, which can has column for each element (default 21) |
| SetTablesType()  | table type name in MySQL database (default "InnoDB") |
| SetUseIndexes()  | usage of indexes in database (default kIndexesBasic) |

Normally these functions should be called immidiately after TSQLFile constructor.
When objects data written to database, by default START TRANSACTION/COMMIT
SQL commands are used before and after data storage. If TSQLFile detects
any problems, ROLLBACK command will be used to restore
previous state of data base. If transactions not supported by SQL server,
they can be disabled by SetUseTransactions(kTransactionsOff). Or user
can take responsibility to use transactions function to hime
By default only indexes for basic tables are created.
In most cases usage of indexes increase perfomance to data reading,
but it also can increase time of writing data to database.
There are several modes of index usage available in SetUseIndexes() method
There is MakeSelectQuery(TClass*) method, which
produces SELECT statement to get objects data of specified class.
Difference from simple statement like:
    mysql> SELECT * FROM TH1I_ver1
that not only data for that class, but also data from parent classes
will be extracted from other tables and combined in single result table.
Such select query can be usufull for external access to objects data.

Up to now MySQL 4.1 and Oracle 9i were tested.
Some extra work is required for other SQL databases.
Hopefully, this should be straigthforward.

Known problems and open questions.
  -# TTree is not supported by TSQLFile. There is independent development
   of TTreeSQL class, which allows to store trees directly in SQL database
  -# TClonesArray is store objects in raw format,
   which can not be accessed outside ROOT.
   This will be changed later.
  -# TDirectory cannot work. Hopefully, will (changes in ROOT basic I/O is required)
  -# Streamer infos are not written to file, therefore schema evolution
   is not yet supported. All eforts are done to enable this feature in
   the near future

### Example how TSQLFile can be used

#### A session saving data to a SQL data base
~~~{.cpp}
auto dbname = "mysql://host.domain:3306/dbname";
auto username = "username";
auto userpass = "userpass";

// Clean data base and create primary tables
auto f = new TSQLFile(dbname, "recreate", username, userpass);
// Write with standard I/O functions
arr->Write("arr", TObject::kSingleKey);
h1->Write("histo");
// Close connection to DB
delete f;
~~~

#### A session read data from SQL data base
~~~{.cpp}
// Open database again in read-only mode
auto f = new TSQLFile(dbname, "open", username, userpass);
// Show list of keys
f->ls();
// Read stored object, again standard ROOT I/O
auto h1 = (TH1*) f->Get("histo");
if (h1!=0) { h1->SetDirectory(0); h1->Draw(); }
auto obj = f->Get("arr");
if (obj!=0) obj->Print("*");
// close connection to DB
delete f;
~~~

The "SQL I/O" package is currently under development.
Any bug reports and suggestions are welcome.
Author: S.Linev, GSI Darmstadt,   S.Linev@gsi.de
*/

#include "TSQLFile.h"

#include "TROOT.h"
#include "TSystem.h"
#include "TList.h"
#include "TBrowser.h"
#include "TObjArray.h"
#include "TObjString.h"
#include "TList.h"
#include "TArrayC.h"
#include "TVirtualStreamerInfo.h"
#include "TStreamerElement.h"
#include "TProcessID.h"
#include "TError.h"
#include "TClass.h"

#include "TSQLServer.h"
#include "TSQLTableInfo.h"
#include "TSQLColumnInfo.h"
#include "TSQLStatement.h"
#include "TSQLResult.h"
#include "TSQLRow.h"
#include "TBufferSQL2.h"
#include "TSQLStructure.h"
#include "TKeySQL.h"
#include "TSQLClassInfo.h"
#include "TSQLObjectData.h"

#include "Riostream.h"

ClassImp(TSQLFile);

const char* mysql_BasicTypes[21] = {
"VARCHAR(255)",     // kBase     =  0,  used for text
"TINYINT UNSIGNED", // kChar     =  1,
"SMALLINT",         // kShort   =  2,
"INT",              // kInt     =  3,
"BIGINT",           // kLong    =  4,
"FLOAT",            // kFloat    = 5,
"INT",              // kCounter =  6,
"VARCHAR(255)",     // kCharStar = 7,
"DOUBLE",           // kDouble   = 8,
"DOUBLE",           // kDouble32=  9,
"",                 // nothing
"TINYINT UNSIGNED", // kUChar    = 11,
"SMALLINT UNSIGNED",// kUShort  = 12,
"INT UNSIGNED",     // kUInt    = 13,
"BIGINT UNSIGNED",  // kULong   = 14,
"INT UNSIGNED",     // kBits     = 15,
"BIGINT",           // kLong64   = 16,
"BIGINT UNSIGNED",  // kULong64 = 17,
"BOOL",             // kBool    = 18,
"DOUBLE",           // kFloat16 = 19,
""
};

const char* mysql_OtherTypes[13] = {
"VARCHAR(255)",     // smallest text
"255",              // maximum length of small text
"TEXT",             // biggest size text
"DATETIME",         // date & time
"`",                // quote for identifier like table name or column name
"dir:id",           // dir id column
"key:id",           // key id column
"obj:id",           // object id column
"raw:id",           // raw data id column
"str:id",           // string id column
":",                // name separator between name and type like TObject:Parent
"\"",               // quote for string values in MySQL
"InnoDB"            // default tables types, used only for MySQL tables
};

const char* oracle_BasicTypes[21] = {
"VARCHAR(255)",     // kBase     =  0,  used for text
"INT",              // kChar     =  1,
"INT",              // kShort   =  2,
"INT",              // kInt     =  3,
"INT",              // kLong    =  4,
"FLOAT",            // kFloat    = 5,
"INT",              // kCounter =  6,
"VARCHAR(255)",     // kCharStar = 7,
"DOUBLE PRECISION", // kDouble   = 8,
"DOUBLE PRECISION", // kDouble32=  9,
"",                 // nothing
"INT",              // kUChar    = 11,
"INT",              // kUShort  = 12,
"INT",              // kUInt    = 13,
"INT",              // kULong   = 14,
"INT",              // kBits     = 15,
"INT",              // kLong64   = 16,
"INT",              // kULong64 = 17,
"INT",              // kBool    = 18,
"FLOAT",            // kFloat16 = 19,
""
};

const char* oracle_OtherTypes[13] = {
"VARCHAR(1000)",    // smallest text
"1000",             // maximum size of smallest text
"VARCHAR(4000)",    // biggest size text, CLOB is not yet supported by TOracleRow
"VARCHAR(50)",      // date & time
"\"",               // quote for identifier like table name or column name
"dir:id",           // dir id column
"key:id",           // key id column
"obj:id",           // object id column
"raw:id",           // raw data id column
"str:id",           // string id column
":",                // name separator between name and type like TObject:parent
"'",                // quote for string values in Oracle
""                  // default tables types, used only for MySQL tables
};


////////////////////////////////////////////////////////////////////////////////
/// default TSQLFile constructor

TSQLFile::TSQLFile() :
   TFile(),
   fSQL(0),
   fSQLClassInfos(0),
   fUseSuffixes(kTRUE),
   fSQLIOversion(1),
   fArrayLimit(21),
   fCanChangeConfig(kFALSE),
   fTablesType(),
   fUseTransactions(0),
   fUseIndexes(0),
   fModifyCounter(0),
   fQuerisCounter(0),
   fBasicTypes(0),
   fOtherTypes(0),
   fUserName(),
   fLogFile(0),
   fIdsTableExists(kFALSE),
   fStmtCounter(0)
{
   SetBit(kBinaryFile, kFALSE);
}

////////////////////////////////////////////////////////////////////////////////
/// Connects to SQL server with provided arguments.
///
/// If the constructor fails in any way IsZombie() will
/// return true. Use IsOpen() to check if the file is (still) open.
/// | Option | Description |
/// |--------|-------------|
/// | NEW or CREATE  | Create a ROOT tables in database if the tables already exists connection is not opened.|
/// | RECREATE       | Create completely new tables. Any existing table will be deleted.|
/// | UPDATE         | Open an existing database for writing. If data base open by other TSQLFile instance for writing, write access will be rejected.|
/// | BREAKLOCK      | Special case when lock was not correctly released by TSQLFile instance. This may happen if program crashed when TSQLFile was open with write access mode.|
/// | READ / OPEN    | Open an existing data base for reading.|
///
/// For more details see comments for TFile::TFile() constructor.
/// For a moment TSQLFile does not support TTree objects and subdirectories.

TSQLFile::TSQLFile(const char* dbname, Option_t* option, const char* user, const char* pass) :
   TFile(),
   fSQL(0),
   fSQLClassInfos(0),
   fUseSuffixes(kTRUE),
   fSQLIOversion(1),
   fArrayLimit(21),
   fCanChangeConfig(kFALSE),
   fTablesType(),
   fUseTransactions(0),
   fUseIndexes(0),
   fModifyCounter(0),
   fQuerisCounter(0),
   fBasicTypes(mysql_BasicTypes),
   fOtherTypes(mysql_OtherTypes),
   fUserName(user),
   fLogFile(0),
   fIdsTableExists(kFALSE),
   fStmtCounter(0)
{
   if (!gROOT)
      ::Fatal("TFile::TFile", "ROOT system not initialized");

   gDirectory = 0;
   SetName(dbname);
   SetTitle("TFile interface to SQL DB");
   TDirectoryFile::Build();
   fFile = this;

   if (dbname && strstr(dbname,"oracle://")!=0) {
      fBasicTypes = oracle_BasicTypes;
      fOtherTypes = oracle_OtherTypes;
   }

   fArrayLimit = 21;
   fTablesType = SQLDefaultTableType();
   fUseIndexes = 1;
   fUseTransactions = kTransactionsAuto;

   fD          = -1;
   fFile       = this;
   fFree       = 0;
   fVersion    = gROOT->GetVersionInt();  //ROOT version in integer format
   fUnits      = 4;
   fOption     = option;
   SetCompressionLevel(5);
   fWritten    = 0;
   fSumBuffer  = 0;
   fSum2Buffer = 0;
   fBytesRead  = 0;
   fBytesWrite = 0;
   fClassIndex = 0;
   fSeekInfo   = 0;
   fNbytesInfo = 0;
   fProcessIDs = 0;
   fNProcessIDs= 0;
   fSeekDir    = sqlio::Ids_RootDir;
   SetBit(kBinaryFile, kFALSE);

   fOption = option;
   fOption.ToUpper();

   if (fOption == "NEW") fOption = "CREATE";

   Bool_t breaklock = kFALSE;

   if (fOption == "BREAKLOCK") { breaklock = kTRUE; fOption = "UPDATE"; }

   Bool_t create   = (fOption == "CREATE") ? kTRUE : kFALSE;
   Bool_t recreate = (fOption == "RECREATE") ? kTRUE : kFALSE;
   Bool_t update   = (fOption == "UPDATE") ? kTRUE : kFALSE;
   Bool_t read     = (fOption == "READ") ? kTRUE : kFALSE;

   if (!create && !recreate && !update && !read) {
      read    = kTRUE;
      fOption = "READ";
   }

   if (!dbname || !dbname[0]) {
      Error("TSQLFile", "Database not specified");
      goto zombie;
   }

   gROOT->cd();

   fSQL = TSQLServer::Connect(dbname, user, pass);

   if (fSQL==0) {
      Error("TSQLFile", "Cannot connect to DB %s", dbname);
      goto zombie;
   }

   if (recreate) {
      if (IsTablesExists())
         if (!IsWriteAccess()) {
            Error("TSQLFile", "no write permission, DB %s locked", dbname);
            goto zombie;
         }
      SQLDeleteAllTables();
      recreate = kFALSE;
      create   = kTRUE;
      fOption  = "CREATE";
   }

   if (create && IsTablesExists()) {
      Error("TSQLFile", "DB tables already exists");
      goto zombie;
   }

   if (update) {
      if (!IsTablesExists()) {
         update = kFALSE;
         create = kTRUE;
      }

      if (update && !breaklock && !IsWriteAccess()) {
         Error("TSQLFile", "no write permission, DB %s locked", dbname);
         goto zombie;
      }
   }

   if (read) {
      if (!IsTablesExists()) {
         Error("TSQLFile", "DB %s tables not exist", dbname);
         goto zombie;
      }
      if (!IsReadAccess()) {
         Error("TSQLFile", "no read permission for DB %s tables", dbname);
         goto zombie;
      }
   }

   fRealName = dbname;

   if (create || update) {
      SetWritable(kTRUE);
      if (update) SetLocking(kLockBusy);
   } else
      SetWritable(kFALSE);

   // user can change configurations only when create (recreate) options
   // was specified. When first object will be saved, configurations will
   // be frozen.
   fCanChangeConfig = create;

   InitSqlDatabase(create);

   return;

zombie:

   delete fSQL;
   fSQL = 0;
   MakeZombie();
   gDirectory = gROOT;
}

////////////////////////////////////////////////////////////////////////////////
/// start logging of all SQL statements in specified file

void TSQLFile::StartLogFile(const char* fname)
{
   StopLogFile();
   fLogFile = new std::ofstream(fname);
}

////////////////////////////////////////////////////////////////////////////////
/// close logging file

void TSQLFile::StopLogFile()
{
   if (fLogFile!=0) {
      delete fLogFile;
      fLogFile = 0;
   }
}

////////////////////////////////////////////////////////////////////////////////
/// checks, if MySQL database

Bool_t TSQLFile::IsMySQL() const
{
   if (fSQL==0) return kFALSE;
   return strcmp(fSQL->ClassName(),"TMySQLServer")==0;
}

////////////////////////////////////////////////////////////////////////////////
/// checks, if Oracle database

Bool_t TSQLFile::IsOracle() const
{
   if (fSQL==0) return kFALSE;
   return strcmp(fSQL->ClassName(),"TOracleServer")==0;
}

////////////////////////////////////////////////////////////////////////////////
/// checks, if ODBC driver used for database connection

Bool_t TSQLFile::IsODBC() const
{
   if (fSQL==0) return kFALSE;
   return strcmp(fSQL->ClassName(),"TODBCServer")==0;

}

////////////////////////////////////////////////////////////////////////////////
/// enable/disable uasge of suffixes in columns names
/// can be changed before first object is saved into file

void TSQLFile::SetUseSuffixes(Bool_t on)
{
   if (!fCanChangeConfig)
      Error("SetUseSuffixes", "Configurations already cannot be changed");
   else
      fUseSuffixes = on;
}

////////////////////////////////////////////////////////////////////////////////
/// Defines maximum number of columns for array representation
/// If array size bigger than limit, array data will be converted to raw format
/// This is usefull to prevent tables with very big number of columns
/// If limit==0, all arrays will be stored in raw format
/// If limit<0, all array values will be stored in column form
/// Default value is 21

void TSQLFile::SetArrayLimit(Int_t limit)
{
   if (!fCanChangeConfig)
      Error("SetArrayLimit", "Configurations already cannot be changed");
   else
      fArrayLimit = limit;
}

////////////////////////////////////////////////////////////////////////////////
/// Defines tables type, which is used in CREATE TABLE statements
/// Now is only used for MySQL database, where following types are supported:
///     "BDB", "HEAP", "ISAM", "InnoDB", "MERGE", "MRG_MYISAM", "MYISAM"
/// Default for TSQLFile is "InnoDB". For more detailes see MySQL docs.

void TSQLFile::SetTablesType(const char* tables_type)
{
   if (!fCanChangeConfig)
      Error("SetTablesType", "Configurations already cannot be changed");
   else
      fTablesType = tables_type;
}

////////////////////////////////////////////////////////////////////////////////
/// Defines usage of transactions statements for writing objects data to database.
/// | Index | Description |
/// |-------|-------------|
/// | kTransactionsOff=0   - no transaction operation are allowed |
/// | kTransactionsAuto=1  - automatic mode. Each write operation, produced by TSQLFile, will be supplied by START TRANSACTION and COMMIT calls. If any error happen, ROLLBACK will returns database to previous state |
/// | kTransactionsUser=2  - transactions are delegated to user. Methods StartTransaction(), Commit() and Rollback() should be called by user. |
///
/// Default UseTransactions option is kTransactionsAuto

void TSQLFile::SetUseTransactions(Int_t mode)
{
   fUseTransactions = mode;
}

////////////////////////////////////////////////////////////////////////////////
/// Start user transaction.
///
/// This can be usesful, when big number of objects should be stored in
/// data base and commitment required only if all operations were successful.
/// In that case in the end of all operations method Commit() should be
/// called. If operation on user-level is looks like not successful,
/// method Rollback() will return database data and TSQLFile instance to
/// previous state.
/// In MySQL not all tables types support transaction mode of operation.
/// See SetTablesType() method for details .

Bool_t TSQLFile::StartTransaction()
{
   if (GetUseTransactions()!=kTransactionsUser) {
      Error("SQLStartTransaction","Only allowed when SetUseTransactions(kUserTransactions) was configured");
      return kFALSE;
   }

   return SQLStartTransaction();
}

////////////////////////////////////////////////////////////////////////////////
/// Commit transaction, started by StartTransaction() call.
/// Only after that call data will be written and visible on database side.

Bool_t TSQLFile::Commit()
{
   if (GetUseTransactions()!=kTransactionsUser) {
      Error("SQLCommit","Only allowed when SetUseTransactions(kUserTransactions) was configured");
      return kFALSE;
   }

   return SQLCommit();
}

////////////////////////////////////////////////////////////////////////////////
/// Rollback all operations, done after StartTransaction() call.
/// Database should return to initial state.

Bool_t TSQLFile::Rollback()
{
   if (GetUseTransactions()!=kTransactionsUser) {
      Error("SQLRollback","Only allowed when SetUseTransactions(kUserTransactions) was configured");
      return kFALSE;
   }

   return SQLRollback();
}

////////////////////////////////////////////////////////////////////////////////
/// Specify usage of indexes for data tables
/// | Index | Description |
/// |-------|-------------|
/// | kIndexesNone = 0  | no indexes are used|
/// | kIndexesBasic = 1 | indexes used only for keys list and objects list tables (default)|
/// | kIndexesClass = 2 | index also created for every normal class table|
/// | kIndexesAll = 3   | index created for every table, including _streamer_ tables|
///
/// Indexes in general should increase speed of access to objects data,
/// but they required more operations and more disk space on server side

void TSQLFile::SetUseIndexes(Int_t use_type)
{
   if (!fCanChangeConfig)
      Error("SetUseIndexes", "Configurations already cannot be changed");
   else
      fUseIndexes = use_type;
}

////////////////////////////////////////////////////////////////////////////////
/// Return name of data base on the host
/// For Oracle always return 0

const char* TSQLFile::GetDataBaseName() const
{
   if (IsOracle()) return 0;
   const char* name = strrchr(GetName(),'/');
   if (name==0) return 0;
   return name + 1;
}

////////////////////////////////////////////////////////////////////////////////
/// Close a SQL file
/// For more comments see TFile::Close() function

void TSQLFile::Close(Option_t *option)
{
   if (!IsOpen()) return;

   TString opt = option;
   if (opt.Length()>0)
      opt.ToLower();

   if (IsWritable()) {
      SaveToDatabase();
      SetLocking(kLockFree);
   }

   fWritable = kFALSE;

   if (fClassIndex) {
      delete fClassIndex;
      fClassIndex = 0;
   }

   {
      TDirectory::TContext ctxt(this);
      // Delete all supported directories structures from memory
      TDirectoryFile::Close();
   }

   //delete the TProcessIDs
   TList pidDeleted;
   TIter next(fProcessIDs);
   TProcessID *pid;
   while ((pid = (TProcessID*)next())) {
      if (!pid->DecrementCount()) {
         if (pid != TProcessID::GetSessionProcessID()) pidDeleted.Add(pid);
      } else if(opt.Contains("r")) {
         pid->Clear();
      }
   }
   pidDeleted.Delete();

   R__LOCKGUARD(gROOTMutex);
   gROOT->GetListOfFiles()->Remove(this);
}

////////////////////////////////////////////////////////////////////////////////
/// destructor of TSQLFile object

TSQLFile::~TSQLFile()
{
   Close();

   if (fSQLClassInfos!=0) {
      fSQLClassInfos->Delete();
      delete fSQLClassInfos;
   }

   StopLogFile();

   if (fSQL!=0) {
      delete fSQL;
      fSQL = 0;
   }
}

////////////////////////////////////////////////////////////////////////////////
/// make private to exclude copy operator

void TSQLFile::operator=(const TSQLFile &)
{
}

////////////////////////////////////////////////////////////////////////////////
/// return kTRUE if file is opened and can be accessed

Bool_t TSQLFile::IsOpen() const
{
   return fSQL != 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Reopen a file with a different access mode, like from READ to
/// See TFile::Open() for details

Int_t TSQLFile::ReOpen(Option_t* mode)
{
   cd();

   TString opt = mode;
   opt.ToUpper();

   if (opt != "READ" && opt != "UPDATE") {
      Error("ReOpen", "mode must be either READ or UPDATE, not %s", opt.Data());
      return 1;
   }

   if (opt == fOption || (opt == "UPDATE" && fOption == "CREATE"))
      return 1;

   if (opt == "READ") {
      // switch to READ mode

      if (IsOpen() && IsWritable()) {
         SaveToDatabase();
         SetLocking(kLockFree);
      }
      fOption = opt;

      SetWritable(kFALSE);

   } else {
      // switch to UPDATE mode

      if (!IsWriteAccess()) {
         Error("ReOpen","Tables are locked, no write access");
         return 1;
      }

      fOption = opt;

      SetWritable(kTRUE);

      SetLocking(kLockBusy);
   }

   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// create SQL key, which will store object in data base

TKey* TSQLFile::CreateKey(TDirectory* mother, const TObject* obj, const char* name, Int_t )
{
   return new TKeySQL(mother, obj, name);
}

////////////////////////////////////////////////////////////////////////////////
/// create SQL key, which will store object in data base

TKey* TSQLFile::CreateKey(TDirectory* mother, const void* obj, const TClass* cl, const char* name, Int_t )
{
   return new TKeySQL(mother, obj, cl, name);
}

////////////////////////////////////////////////////////////////////////////////
/// Write file info like configurations, title, UUID and other

void TSQLFile::WriteHeader()
{
   WriteSpecialObject(sqlio::Ids_TSQLFile, this, GetName(), GetTitle());
}

////////////////////////////////////////////////////////////////////////////////
/// Store all TVirtualStreamerInfo, used in file, in sql database

void TSQLFile::WriteStreamerInfo()
{
   // return;

   // do not write anything when no basic tables was created
   if (!IsTablesExists()) return;

   if (gDebug>1)
      Info("WriteStreamerInfo","Saving streamer infos to database");

   TList list;

   TIter iter(gROOT->GetListOfStreamerInfo());

   TVirtualStreamerInfo* info = 0;

   while ((info = (TVirtualStreamerInfo*) iter()) !=0 ) {
      Int_t uid = info->GetNumber();
      if (fClassIndex->fArray[uid]) {
         if (gDebug>1) Info("WriteStreamerInfo","Add %s",info->GetName());
         list.Add(info);
      }
   }
   if (list.GetSize()==0) return;
   fClassIndex->fArray[0] = 2; //to prevent adding classes in TVirtualStreamerInfo::TagFile

   WriteSpecialObject(sqlio::Ids_StreamerInfos, &list, "StreamerInfo", "StreamerInfos of this file");

   fClassIndex->fArray[0] = 0; //to prevent adding classes in TVirtualStreamerInfo::TagFile
}

////////////////////////////////////////////////////////////////////////////////
/// write special kind of object like streamer infos or file itself
/// keys for that objects should exist in tables but not indicated in list of keys,
/// therefore users can not get them with TDirectoryFile::Get() method

Bool_t TSQLFile::WriteSpecialObject(Long64_t keyid, TObject* obj, const char* name, const char* title)
{
   DeleteKeyFromDB(keyid);
   if (obj==0) return kTRUE;

   Long64_t objid = StoreObjectInTables(keyid, obj, obj->IsA());

   if (objid>0) {
      TDatime now;

      TKeySQL* key = new TKeySQL(this, keyid, objid,
                                 name, title,
                                 now.AsSQLString(), 1, obj->ClassName());
      WriteKeyData(key);
      delete key;
   }

   return (objid>0);
}

////////////////////////////////////////////////////////////////////////////////
/// Read data of special kind of objects

TObject* TSQLFile::ReadSpecialObject(Long64_t keyid, TObject* obj)
{
   TKeySQL* key = 0;

   StreamKeysForDirectory(this, kFALSE, keyid, &key);
   if (key==0) return obj;

   TBufferSQL2 buffer(TBuffer::kRead, this);

   TClass* cl = 0;

   void* res = buffer.SqlReadAny(key->GetDBKeyId(), key->GetDBObjId(), &cl, obj);

   if ((cl==TSQLFile::Class()) && (res!=0) && (obj==this)) {
      // name should not be preserved while name of database may be changed
      SetTitle(key->GetTitle());
   }

   delete key;

   return (TObject*) res;
}

////////////////////////////////////////////////////////////////////////////////
/// Read back streamer infos from database
/// List of streamer infos is always stored with key:id 0,
/// which is not shown in normal keys list

TList* TSQLFile::GetStreamerInfoList()
{
//   return new TList;

   if (gDebug>1)
      Info("GetStreamerInfoList","Start reading of streamer infos");

   TObject* obj = ReadSpecialObject(sqlio::Ids_StreamerInfos);

   TList* list = dynamic_cast<TList*> (obj);
   if (list==0) { delete obj; list = new TList; }

   return list;
}

////////////////////////////////////////////////////////////////////////////////
/// save data which is not yet in Database
/// Typically this is streamerinfos structures or

void TSQLFile::SaveToDatabase()
{
   if (fSQL==0) return;

   WriteStreamerInfo();
   WriteHeader();
}

////////////////////////////////////////////////////////////////////////////////
/// read keys for specified directory (when update == kFALSE)
/// or update value for modified keys when update == kTRUE
/// Returns number of successfully read keys or -1 if error

Int_t TSQLFile::StreamKeysForDirectory(TDirectory* dir, Bool_t doupdate, Long64_t specialkeyid, TKeySQL** specialkey)
{
   if (dir==0) return -1;

   const char* quote = SQLIdentifierQuote();

   Long64_t dirid = dir->GetSeekDir();

   TString sqlcmd;
   sqlcmd.Form("SELECT * FROM %s%s%s WHERE %s%s%s=%lld",
               quote, sqlio::KeysTable, quote,
               quote, SQLDirIdColumn(), quote, dirid);
   if (specialkeyid>=0) {
      TString buf;
      buf.Form(" AND %s%s%s=%lld", quote, SQLKeyIdColumn(), quote, specialkeyid);
      sqlcmd += buf;
   }

   TSQLResult* res = SQLQuery(sqlcmd.Data(), 2);

   if (res==0) return -1;

   Int_t nkeys = 0;

   TSQLRow* row = 0;

   while ((row = res->Next()) != 0) {
      nkeys++;

      Long64_t keyid = sqlio::atol64((*row)[0]);
      //      Int_t dirid = atoi((*row)[1]);
      Long64_t objid = sqlio::atol64((*row)[2]);
      const char* keyname = (*row)[3];
      const char* keytitle = (*row)[4];
      const char* keydatime = (*row)[5];
      Int_t cycle = atoi((*row)[6]);
      const char* classname = (*row)[7];

      if (gDebug>4)
        std::cout << "  Reading keyid = " << keyid << " name = " << keyname << std::endl;

      if ((keyid>=sqlio::Ids_FirstKey) || (keyid==specialkeyid)) {
         if (doupdate) {
            TKeySQL* key = FindSQLKey(dir, keyid);

            if (key==0) {
               Error("StreamKeysForDirectory","Key with id %lld not exist in list", keyid);
               nkeys = -1; // this will finish execution
            } else
            if (key->IsKeyModified(keyname, keytitle, keydatime, cycle, classname))
               UpdateKeyData(key);

         } else {
            TKeySQL* key = new TKeySQL(dir, keyid, objid,
                                       keyname, keytitle,
                                       keydatime, cycle, classname);
            if (specialkey!=0)
               { *specialkey = key; nkeys = 1; }
            else
               dir->GetListOfKeys()->Add(key);
         }
      }
      delete row;
   }

   delete res;

   if (gDebug>4) {
      Info("StreamKeysForDirectory","dir = %s numread = %d",dir->GetName(), nkeys);
      dir->GetListOfKeys()->Print("*");
   }

   return nkeys;
}

////////////////////////////////////////////////////////////////////////////////
/// initialize sql database and correspondent structures
/// identical to TFile::Init() function

void TSQLFile::InitSqlDatabase(Bool_t create)
{
   Int_t len = gROOT->GetListOfStreamerInfo()->GetSize()+1;
   if (len<5000) len = 5000;
   fClassIndex = new TArrayC(len);
   fClassIndex->Reset(0);

   if (!create) {

      Bool_t ok = ReadConfigurations();

      // read data corresponding to TSQLFile
      if (ok) {
         ReadSQLClassInfos();

         ReadStreamerInfo();

         ok = (ReadSpecialObject(sqlio::Ids_TSQLFile, this) != 0);
      }

      // read list of keys
      if (ok)
         ok = StreamKeysForDirectory(this, kFALSE)>=0;

      if (!ok) {
         Error("InitSqlDatabase", "Cannot detect proper tabled in database. Close.");
         Close();
         delete fSQL;
         fSQL = 0;
         MakeZombie();
         gDirectory = gROOT;
         return;
      }
   }

   {
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfFiles()->Add(this);
   }
   cd();

   fNProcessIDs = 0;
   TKey* key = 0;
   TIter iter(fKeys);
   while ((key = (TKey*)iter())!=0) {
      if (!strcmp(key->GetClassName(),"TProcessID")) fNProcessIDs++;
   }

   fProcessIDs = new TObjArray(fNProcessIDs+1);
}

////////////////////////////////////////////////////////////////////////////////
/// read table configurations as special table

Bool_t TSQLFile::ReadConfigurations()
{
   const char* quote = SQLIdentifierQuote();

   TString sqlcmd;
   sqlcmd.Form("SELECT * FROM %s%s%s",
               quote, sqlio::ConfigTable, quote);
   TSQLResult* res = SQLQuery(sqlcmd.Data(), 2);

   if (res==0) return kFALSE;

   // should be found, otherwise will be error
   fSQLIOversion = 0;

   Int_t lock = 0;

   #define ReadIntCfg(name, target)                        \
     if ((field.CompareTo(name, TString::kIgnoreCase)==0)) \
        target = value.Atoi(); else

   #define ReadBoolCfg(name, target)                        \
     if ((field.CompareTo(name, TString::kIgnoreCase)==0))  \
        target = value.CompareTo(sqlio::True, TString::kIgnoreCase)==0; else

   #define ReadStrCfg(name, target)                         \
     if ((field.CompareTo(name, TString::kIgnoreCase)==0))  \
        target = value; else

   TSQLRow* row = 0;

   while ((row = res->Next()) != 0) {

      TString field = row->GetField(0);
      TString value = row->GetField(1);

      delete row;

      ReadIntCfg(sqlio::cfg_Version, fSQLIOversion)
      ReadBoolCfg(sqlio::cfg_UseSufixes, fUseSuffixes)
      ReadIntCfg(sqlio::cfg_ArrayLimit, fArrayLimit)
      ReadStrCfg(sqlio::cfg_TablesType, fTablesType)
      ReadIntCfg(sqlio::cfg_UseTransactions, fUseTransactions)
      ReadIntCfg(sqlio::cfg_UseIndexes, fUseIndexes)
      ReadIntCfg(sqlio::cfg_ModifyCounter, fModifyCounter)
      ReadIntCfg(sqlio::cfg_LockingMode, lock)
      {
         Error("ReadConfigurations","Invalid configuration field %s", field.Data());
         fSQLIOversion = 0;
         break;
      }
   }
   (void)lock;

   delete res;

   return (fSQLIOversion>0);
}

////////////////////////////////////////////////////////////////////////////////
/// Creates initial tables in database
/// This is table with configurations and table with keys
/// Function called once when first object is stored to the file.

void TSQLFile::CreateBasicTables()
{
   TString sqlcmd;

   const char* quote = SQLIdentifierQuote();
   const char* vquote = SQLValueQuote();

   if (SQLTestTable(sqlio::ConfigTable)) {
      sqlcmd.Form("DROP TABLE %s%s%s", quote, sqlio::ConfigTable, quote);
      SQLQuery(sqlcmd.Data());
   }

   sqlcmd.Form("CREATE TABLE %s%s%s (%s%s%s %s, %s%s%s %s)",
               quote, sqlio::ConfigTable, quote,
               quote, sqlio::CT_Field, quote, SQLSmallTextType(),
               quote, sqlio::CT_Value, quote, SQLSmallTextType());
   if ((fTablesType.Length()>0) && IsMySQL()) {
      sqlcmd +=" ENGINE=";
      sqlcmd += fTablesType;
   }

   SQLQuery(sqlcmd.Data());

   #define WrintCfg(name, type, value)                              \
   {                                                                \
      sqlcmd.Form("INSERT INTO %s%s%s VALUES (%s%s%s, %s" type "%s)", \
                  quote, sqlio::ConfigTable, quote,                 \
                  vquote, name, vquote,                             \
                  vquote, value, vquote);                           \
      SQLQuery(sqlcmd.Data());                                      \
   }

   WrintCfg(sqlio::cfg_Version, "%d", fSQLIOversion);
   WrintCfg(sqlio::cfg_UseSufixes, "%s", fUseSuffixes ? sqlio::True : sqlio::False);
   WrintCfg(sqlio::cfg_ArrayLimit, "%d", fArrayLimit);
   WrintCfg(sqlio::cfg_TablesType, "%s", fTablesType.Data());
   WrintCfg(sqlio::cfg_UseTransactions, "%d", fUseTransactions);
   WrintCfg(sqlio::cfg_UseIndexes, "%d", fUseIndexes);
   WrintCfg(sqlio::cfg_ModifyCounter, "%d", fModifyCounter);
   WrintCfg(sqlio::cfg_LockingMode, "%d", kLockBusy);

   // from this moment on user cannot change configurations
   fCanChangeConfig = kFALSE;

   if (SQLTestTable(sqlio::KeysTable)) {
      sqlcmd.Form("DROP TABLE %s%s%s", quote, sqlio::KeysTable, quote);
      SQLQuery(sqlcmd.Data());
   }

   sqlcmd.Form("CREATE TABLE %s%s%s (%s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s)",
               quote, sqlio::KeysTable, quote,
               quote, SQLKeyIdColumn(), quote, SQLIntType(),
               quote, SQLDirIdColumn(), quote, SQLIntType(),
               quote, SQLObjectIdColumn(), quote, SQLIntType(),
               quote, sqlio::KT_Name, quote, SQLSmallTextType(),
               quote, sqlio::KT_Title, quote, SQLSmallTextType(),
               quote, sqlio::KT_Datetime, quote, SQLDatetimeType(),
               quote, sqlio::KT_Cycle, quote, SQLIntType(),
               quote, sqlio::KT_Class, quote, SQLSmallTextType());

   if ((fTablesType.Length()>0) && IsMySQL()) {
      sqlcmd +=" ENGINE=";
      sqlcmd += fTablesType;
   }

   SQLQuery(sqlcmd.Data());

   if (GetUseIndexes()>kIndexesNone) {
      sqlcmd.Form("CREATE UNIQUE INDEX %s%s%s ON %s%s%s (%s%s%s)",
                   quote, sqlio::KeysTableIndex, quote,
                   quote, sqlio::KeysTable, quote,
                   quote, SQLKeyIdColumn(), quote);
      SQLQuery(sqlcmd.Data());
   }
}

////////////////////////////////////////////////////////////////////////////////
/// Update value of modify counter in config table
/// Modify counter used to indicate that something was changed in database.
/// It will be used when multiple instances of TSQLFile for the same data base
/// will be connected.

void TSQLFile::IncrementModifyCounter()
{
   if (!IsWritable()) {
      Error("IncrementModifyCounter","Cannot update tables without write accsess");
      return;
   }

   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();
   const char* vquote = SQLValueQuote();

   sqlcmd.Form("UPDATE %s%s%s SET %s%s%s=%d WHERE %s%s%s=%s%s%s",
                quote, sqlio::ConfigTable, quote,
                quote, sqlio::CT_Value, quote, ++fModifyCounter,
                quote, sqlio::CT_Field, quote,
                vquote, sqlio::cfg_ModifyCounter, vquote);
   SQLQuery(sqlcmd.Data());
}

////////////////////////////////////////////////////////////////////////////////
/// Produce \b SELECT statement which can be used to get all data
/// of class cl in one \b SELECT statement.
///
/// This statement also can be used to create \b VIEW by command like
///     mysql> CREATE VIEW TH1I_view AS $CLASSSELECT$
/// Where \b $CLASSSELECT$ argument should be produced by call
///     f->MakeSelectQuery(TH1I::Class());
/// \b VIEWs supported by latest MySQL 5 and Oracle

TString TSQLFile::MakeSelectQuery(TClass* cl)
{
   TString res = "";
   TSQLClassInfo* sqlinfo = FindSQLClassInfo(cl);
   if (sqlinfo==0) return res;

   TString columns, tables;
   Int_t tablecnt = 0;

   if (!ProduceClassSelectQuery(cl->GetStreamerInfo(), sqlinfo, columns, tables, tablecnt))
      return res;

   res.Form("SELECT %s FROM %s", columns.Data(), tables.Data());

   return res;
}

////////////////////////////////////////////////////////////////////////////////
/// used by MakeClassSelectQuery method to add columns from table of
/// class, specified by TVirtualStreamerInfo structure

Bool_t TSQLFile::ProduceClassSelectQuery(TVirtualStreamerInfo* info,
                                         TSQLClassInfo* sqlinfo,
                                         TString& columns,
                                         TString& tables,
                                         Int_t& tablecnt)
{
   if ((info==0) || (sqlinfo==0)) return kFALSE;

   if (!sqlinfo->IsClassTableExist()) return kFALSE;

   const char* quote = SQLIdentifierQuote();

   TString table_syn;
   table_syn.Form("t%d", ++tablecnt);

   Bool_t start = tables.Length()==0;

   TString buf;

   if (start)
      buf.Form("%s AS %s", sqlinfo->GetClassTableName(), table_syn.Data());
   else
      buf.Form(" LEFT JOIN %s AS %s USING(%s%s%s)",
               sqlinfo->GetClassTableName(), table_syn.Data(),
               quote, SQLObjectIdColumn(), quote);

   tables += buf;

   if (start)
      columns.Form("%s.%s%s%s",table_syn.Data(), quote, SQLObjectIdColumn(), quote);

   if (info->GetClass()==TObject::Class()) {
      buf.Form(", %s.%s",table_syn.Data(), sqlio::TObjectUniqueId);
      columns+=buf;
      buf.Form(", %s.%s",table_syn.Data(), sqlio::TObjectBits);
      columns+=buf;
      buf.Form(", %s.%s",table_syn.Data(), sqlio::TObjectProcessId);
      columns+=buf;
      return kTRUE;
   }

   TIter iter(info->GetElements());
   TStreamerElement* elem = 0;

   while ((elem = (TStreamerElement*) iter()) != 0) {
      Int_t coltype = TSQLStructure::DefineElementColumnType(elem, this);
      TString colname = TSQLStructure::DefineElementColumnName(elem, this);

      buf = "";
      switch (coltype) {

         case TSQLStructure::kColObject:
         case TSQLStructure::kColObjectPtr:
         case TSQLStructure::kColTString:
         case TSQLStructure::kColSimple: {
            buf.Form(", %s.%s%s%s",table_syn.Data(), quote, colname.Data(), quote);
            columns+=buf;
            break;
         }

         case TSQLStructure::kColParent: {
            TClass* parentcl = elem->GetClassPointer();
            ProduceClassSelectQuery(parentcl->GetStreamerInfo(),
                                    FindSQLClassInfo(parentcl),
                                    columns, tables, tablecnt);
            break;
         }

         case TSQLStructure::kColSimpleArray: {
            for(Int_t n=0;n<elem->GetArrayLength();n++) {
               colname = TSQLStructure::DefineElementColumnName(elem, this, n);
               buf.Form(", %s.%s%s%s",table_syn.Data(), quote, colname.Data(), quote);
               columns+=buf;
            }
            break;
         }
      } // switch
   }

   return (columns.Length()>0) && (tables.Length()>0);
}

////////////////////////////////////////////////////////////////////////////////
/// Checks if main keys table is existing

Bool_t TSQLFile::IsTablesExists()
{
   return SQLTestTable(sqlio::KeysTable) && SQLTestTable(sqlio::ConfigTable);
}

////////////////////////////////////////////////////////////////////////////////
/// Checkis, if lock is free in configuration tables

Bool_t TSQLFile::IsWriteAccess()
{
   return GetLocking()==kLockFree;
}

////////////////////////////////////////////////////////////////////////////////
/// Set locking mode for current database

void TSQLFile::SetLocking(Int_t mode)
{
   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();
   const char* vquote = SQLValueQuote();

   sqlcmd.Form("UPDATE %s%s%s SET %s%s%s=%d WHERE %s%s%s=%s%s%s",
                quote, sqlio::ConfigTable, quote,
                quote, sqlio::CT_Value, quote, mode,
                quote, sqlio::CT_Field, quote,
                vquote, sqlio::cfg_LockingMode, vquote);
   SQLQuery(sqlcmd.Data());
}

////////////////////////////////////////////////////////////////////////////////
/// Return current locking mode for that file

Int_t TSQLFile::GetLocking()
{
   const char* quote = SQLIdentifierQuote();
   const char* vquote = SQLValueQuote();

   TString sqlcmd;
   sqlcmd.Form("SELECT %s%s%s FROM %s%s%s WHERE %s%s%s=%s%s%s",
                quote, sqlio::CT_Value, quote,
                quote, sqlio::ConfigTable, quote,
                quote, sqlio::CT_Field, quote,
                vquote, sqlio::cfg_LockingMode, vquote);

   TSQLResult* res = SQLQuery(sqlcmd.Data(), 1);
   TSQLRow* row = (res==0) ? 0 : res->Next();
   TString field = (row==0) ? "" : row->GetField(0);
   delete row;
   delete res;

   if (field.Length()==0) return kLockFree;

   return field.Atoi();
}

////////////////////////////////////////////////////////////////////////////////
/// dummy, in future should check about read access to database

Bool_t TSQLFile::IsReadAccess()
{
   return kTRUE;
}

////////////////////////////////////////////////////////////////////////////////
/// Submits query to SQL server.
///
/// | Flag Value | Effect|
/// |------------|-------|
/// | 0 | result is not interesting and will be deleted|
/// | 1 | return result of submitted query
/// | 2 | results is may be necessary for long time Oracle plugin do not support working with several TSQLResult objects, therefore explicit deep copy will be produced|
///
/// If ok!=0, it will contains kTRUE is Query was successfull, otherwise kFALSE

TSQLResult* TSQLFile::SQLQuery(const char* cmd, Int_t flag, Bool_t* ok)
{
   if (fLogFile!=0)
      *fLogFile << cmd << std::endl;

   if (ok!=0) *ok = kFALSE;

   if (fSQL==0) return 0;

   if (gDebug>2) Info("SQLQuery", "%s", cmd);

   fQuerisCounter++;

   if (flag==0) {
      Bool_t res = fSQL->Exec(cmd);
      if (ok!=0) *ok = res;
      return 0;
   }

   TSQLResult* res = fSQL->Query(cmd);
   if (ok!=0) *ok = res!=0;
   if (res==0) return 0;
//   if ((flag==2) && IsOracle())
//      res = new TSQLResultCopy(res);
   return res;
}

////////////////////////////////////////////////////////////////////////////////
/// Test if DB support statement and number of open statements is not exceeded

Bool_t TSQLFile::SQLCanStatement()
{
   if (fSQL==0) return kFALSE;

   if (!fSQL->HasStatement()) return kFALSE;

   return kTRUE; // !IsOracle() || (fStmtCounter<15);
}

////////////////////////////////////////////////////////////////////////////////
/// Produces SQL statement for currently conected DB server

TSQLStatement* TSQLFile::SQLStatement(const char* cmd, Int_t bufsize)
{
   if (fSQL==0) return 0;

   if (!fSQL->HasStatement()) return 0;

   if (gDebug>1)
      Info("SQLStatement", "%s", cmd);

   fStmtCounter++;
   fQuerisCounter++; // one statement counts as one query

   return fSQL->Statement(cmd, bufsize);
}

////////////////////////////////////////////////////////////////////////////////
/// delete statement and decrease counter

void TSQLFile::SQLDeleteStatement(TSQLStatement* stmt)
{
   if (stmt==0) return;

   fStmtCounter--;

   delete stmt;
}

////////////////////////////////////////////////////////////////////////////////
/// supplies set of commands to server
/// Commands is stored as array of TObjString

Bool_t TSQLFile::SQLApplyCommands(TObjArray* cmds)
{
   if ((cmds==0) || (fSQL==0)) return kFALSE;

   Bool_t ok = kTRUE;
   TIter iter(cmds);
   TObject* cmd= 0;
   while ((cmd=iter())!=0) {
      SQLQuery(cmd->GetName(),0,&ok);
      if(!ok) break;
   }

   return ok;
}

////////////////////////////////////////////////////////////////////////////////
/// Test, if table of specified name exists

Bool_t TSQLFile::SQLTestTable(const char* tablename)
{
   if (fSQL==0) return kFALSE;

   if (fSQL->HasTable(tablename)) return kTRUE;

   TString buf(tablename);
   buf.ToLower();
   if (fSQL->HasTable(buf.Data())) return kTRUE;
   buf.ToUpper();
   return fSQL->HasTable(buf.Data());
}

////////////////////////////////////////////////////////////////////////////////
/// Returns maximum value, found in specified columnname of table tablename
/// Column type should be numeric

Long64_t TSQLFile::SQLMaximumValue(const char* tablename, const char* columnname)
{
   if (fSQL==0) return -1;

   if (gDebug>2)
      Info("SQLMaximumValue","Requests for %s column %s", tablename, columnname);

   const char* quote = SQLIdentifierQuote();

   TString query;
   query.Form("SELECT MAX(%s%s%s) FROM %s%s%s",
              quote, columnname, quote,
              quote, tablename, quote);
   TSQLResult* res = SQLQuery(query.Data(), 1);

   if (res==0) return -1;

   TSQLRow* row = res->Next();

   Long64_t maxid = -1;
   if (row!=0)
      if (row->GetField(0)!=0)
         maxid = sqlio::atol64(row->GetField(0));

   delete row;
   delete res;

   if (gDebug>2)
      Info("SQLMaximumValue","Result = %lld",maxid);;

   return maxid;
}

////////////////////////////////////////////////////////////////////////////////
/// Delete all tables in database

void TSQLFile::SQLDeleteAllTables()
{
   if (fSQL==0) return;

   TList* tables = fSQL->GetTablesList();
   if (tables==0) return;

   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();

   TIter iter(tables);
   TObject* obj = 0;
   while ((obj=iter())!=0) {
      sqlcmd.Form("DROP TABLE %s%s%s", quote, obj->GetName(), quote);
      SQLQuery(sqlcmd.Data());
   }
   delete tables;
}

////////////////////////////////////////////////////////////////////////////////
/// Start SQL transaction.

Bool_t TSQLFile::SQLStartTransaction()
{
   return fSQL ? fSQL->StartTransaction() : kFALSE;
}

////////////////////////////////////////////////////////////////////////////////
/// Commit SQL transaction

Bool_t TSQLFile::SQLCommit()
{
   return fSQL ? fSQL->Commit() : kFALSE;
}

////////////////////////////////////////////////////////////////////////////////
/// Rollback all SQL operations, done after start transaction

Bool_t TSQLFile::SQLRollback()
{
   return fSQL ? fSQL->Rollback() : kFALSE;
}

////////////////////////////////////////////////////////////////////////////////
/// returns maximum allowed length of identifiers

Int_t TSQLFile::SQLMaxIdentifierLength()
{
   Int_t maxlen = fSQL==0 ? 32 : fSQL->GetMaxIdentifierLength();

   // lets exclude absolute ubnormal data
   if (maxlen<10) maxlen = 10;

   return maxlen;
}

////////////////////////////////////////////////////////////////////////////////
/// Remove key with specified id from keys table
/// also removes all objects data, related to this table

void TSQLFile::DeleteKeyFromDB(Long64_t keyid)
{
   if (!IsWritable() || (keyid<0) || (fSQL==0)) return;

   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();

   sqlcmd.Form("SELECT MIN(%s%s%s), MAX(%s%s%s) FROM %s%s%s WHERE %s%s%s=%lld",
               quote, SQLObjectIdColumn(), quote,
               quote, SQLObjectIdColumn(), quote,
               quote, sqlio::ObjectsTable, quote,
               quote, SQLKeyIdColumn(), quote, keyid);
   TSQLResult* res = SQLQuery(sqlcmd.Data(), 2);
   TSQLRow* row = res==0 ? 0 : res->Next();
   Long64_t minid(1), maxid(0);

   if ((row!=0) && (row->GetField(0)!=0) && (row->GetField(1)!=0)) {
      minid = sqlio::atol64(row->GetField(0));
      maxid = sqlio::atol64(row->GetField(1));
   }

   delete row;
   delete res;

   // can be that object tables does not include any entry this that keyid
   if (minid<=maxid) {
      TIter iter(fSQLClassInfos);
      TSQLClassInfo* info = 0;
      TString querymask, query;
      querymask.Form("DELETE FROM %s%s%s WHERE %s%s%s BETWEEN %lld AND %lld",
                     quote, "%s", quote,
                     quote, SQLObjectIdColumn(), quote,
                     minid, maxid);

      while ((info = (TSQLClassInfo*) iter()) !=0 ) {

         if (info->IsClassTableExist()) {
            query.Form(querymask.Data(), info->GetClassTableName());
            SQLQuery(query.Data());
         }

         if (info->IsRawTableExist()) {
            query.Form(querymask.Data(), info->GetRawTableName());
            SQLQuery(query.Data());
         }
      }
   }

   sqlcmd.Form("DELETE FROM %s%s%s WHERE %s%s%s=%lld", quote, sqlio::ObjectsTable, quote, quote, SQLKeyIdColumn(), quote, keyid);
   SQLQuery(sqlcmd.Data());

   sqlcmd.Form("DELETE FROM %s%s%s WHERE %s%s%s=%lld", quote, sqlio::KeysTable, quote, quote, SQLKeyIdColumn(), quote, keyid);
   SQLQuery(sqlcmd.Data());

   IncrementModifyCounter();
}

////////////////////////////////////////////////////////////////////////////////
/// Search for TKeySQL object with specified keyid

TKeySQL* TSQLFile::FindSQLKey(TDirectory* dir, Long64_t keyid)
{
   if (dir==0) return 0;

   TIter next(dir->GetListOfKeys());
   TObject* obj = 0;

   while ((obj = next())!=0) {
      TKeySQL* key = dynamic_cast<TKeySQL*> (obj);
      if (key!=0)
         if (key->GetDBKeyId()==keyid) return key;
   }

   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Add entry into keys table

Bool_t TSQLFile::WriteKeyData(TKeySQL* key)
{
   if ((fSQL==0) || (key==0)) return kFALSE;

   if (!IsTablesExists()) CreateBasicTables();

   TString sqlcmd;
   const char* valuequote = SQLValueQuote();
   const char* quote = SQLIdentifierQuote();

   sqlcmd.Form("INSERT INTO %s%s%s VALUES (%lld, %lld, %lld, %s%s%s, %s%s%s, %s%s%s, %d, %s%s%s)",
               quote, sqlio::KeysTable, quote,
               key->GetDBKeyId(), key->GetDBDirId(), key->GetDBObjId(),
               valuequote, key->GetName(), valuequote,
               valuequote, key->GetTitle(), valuequote,
               valuequote, key->GetDatime().AsSQLString(), valuequote,
               key->GetCycle(),
               valuequote, key->GetClassName(), valuequote);

   Bool_t ok = kTRUE;

   SQLQuery(sqlcmd.Data(), 0, &ok);

   if (ok) IncrementModifyCounter();

   return ok;
}

////////////////////////////////////////////////////////////////////////////////
/// Updates (overwrites) key data in KeysTable

Bool_t TSQLFile::UpdateKeyData(TKeySQL* key)
{
   if ((fSQL==0) || (key==0)) return kFALSE;

   TString sqlcmd;
   const char* valuequote = SQLValueQuote();
   const char* quote = SQLIdentifierQuote();

   TString keyname = key->GetName();
   TString keytitle = key->GetTitle();
   TString keydatime = key->GetDatime().AsSQLString();

   TSQLStructure::AddStrBrackets(keyname, valuequote);
   TSQLStructure::AddStrBrackets(keytitle, valuequote);
   TSQLStructure::AddStrBrackets(keydatime, valuequote);

   sqlcmd.Form("UPDATE %s%s%s SET %s%s%s=%s, %s%s%s=%s, %s%s%s=%s, %s%s%s=%d WHERE %s%s%s=%lld",
                quote, sqlio::KeysTable, quote,
                quote, sqlio::KT_Name, quote, keyname.Data(),
                quote, sqlio::KT_Title, quote, keytitle.Data(),
                quote, sqlio::KT_Datetime, quote, keydatime.Data(),
                quote, sqlio::KT_Cycle, quote, key->GetCycle(),
                quote, SQLKeyIdColumn(), quote, key->GetDBKeyId());

   Bool_t ok = kTRUE;

   SQLQuery(sqlcmd.Data(), 0, &ok);

   if (ok) IncrementModifyCounter();

   return ok;
}

////////////////////////////////////////////////////////////////////////////////
/// Returns next possible key identifier

Long64_t TSQLFile::DefineNextKeyId()
{
   Long64_t max = -1;

   if (SQLTestTable(sqlio::KeysTable))
      max = SQLMaximumValue(sqlio::KeysTable, SQLKeyIdColumn());

   if (max<0) return sqlio::Ids_FirstKey;

   return max+1;
}

////////////////////////////////////////////////////////////////////////////////
/// Return (if exists) TSQLClassInfo for specified class name and version

TSQLClassInfo* TSQLFile::FindSQLClassInfo(const char* clname, Int_t version)
{
   if (fSQLClassInfos==0) return 0;

   TIter iter(fSQLClassInfos);
   TSQLClassInfo* info = 0;

   while ((info = (TSQLClassInfo*) iter()) !=0 ) {
      if (strcmp(info->GetName(), clname)==0)
         if (info->GetClassVersion()==version) return info;
   }
   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// return (if exists) TSQLClassInfo for specified class

TSQLClassInfo* TSQLFile::FindSQLClassInfo(const TClass* cl)
{
   return FindSQLClassInfo(cl->GetName(), cl->GetClassVersion());
}

////////////////////////////////////////////////////////////////////////////////
/// Search in database tables for specified class and return TSQLClassInfo object

TSQLClassInfo* TSQLFile::RequestSQLClassInfo(const char* clname, Int_t version)
{
   TSQLClassInfo* info = FindSQLClassInfo(clname, version);
   if (info!=0) return info;

   if (fSQL==0) return 0;

   Long64_t maxid = 0;

   if (fSQLClassInfos!=0) {
      TIter iter(fSQLClassInfos);
      info = 0;
      while ((info = (TSQLClassInfo*) iter()) !=0 ) {
         if (info->GetClassId()>maxid)
            maxid = info->GetClassId();
      }
   }

   info = new TSQLClassInfo(maxid+1, clname, version);

   info->SetClassTableName(DefineTableName(clname, version, kFALSE));
   info->SetRawTableName(DefineTableName(clname, version, kTRUE));

   if (fSQLClassInfos==0) fSQLClassInfos = new TList;
   fSQLClassInfos->Add(info);

   return info;
}

////////////////////////////////////////////////////////////////////////////////
/// Proposes table name for class

TString TSQLFile::DefineTableName(const char* clname, Int_t version, Bool_t rawtable)
{
   Int_t maxlen = SQLMaxIdentifierLength();

   TString res;

   const char *suffix = rawtable ? "_raw" : "_ver";

   res.Form("%s%s%d", clname, suffix, version);

   if ((res.Length() <= maxlen) && !HasTable(res.Data()))
      return res;

   TString scnt;

   Int_t len = strlen(clname);
   Int_t cnt = version;
   if (cnt>100) cnt = 0; // do not start with the biggest values

   do {
      scnt.Form("%d%s",cnt, suffix);
      Int_t numlen = scnt.Length();
      if (numlen>=maxlen-2) break;

      res = clname;

      if (len + numlen > maxlen)
         res.Resize(maxlen - numlen);

      res+=scnt;

      if (!HasTable(res.Data())) return res;

      cnt++;

   } while (cnt<10000);

   Error("DefineTableName","Cannot produce table name for class %s ver %d", clname, version);
   res.Form("%s%s%d", clname, suffix, version);

   return res;
}

////////////////////////////////////////////////////////////////////////////////
/// Test if table name exists

Bool_t TSQLFile::HasTable(const char* name)
{
   if (fSQLClassInfos==0) return kFALSE;

   TIter iter(fSQLClassInfos);
   TSQLClassInfo* info = 0;
   while ((info = (TSQLClassInfo*) iter()) !=0 ) {
      if (strcmp(info->GetClassTableName(), name)==0) return kTRUE;
      if (strcmp(info->GetRawTableName(), name)==0) return kTRUE;
   }

   return kFALSE;
}

////////////////////////////////////////////////////////////////////////////////
/// Search in database tables for specified class and return TSQLClassInfo object

TSQLClassInfo* TSQLFile::RequestSQLClassInfo(const TClass* cl)
{
   return RequestSQLClassInfo(cl->GetName(), cl->GetClassVersion());
}

////////////////////////////////////////////////////////////////////////////////
/// Read all class infos from IdsTable

void TSQLFile::ReadSQLClassInfos()
{
   if (fSQL==0) return;

   fIdsTableExists = SQLTestTable(sqlio::IdsTable);

   if (!fIdsTableExists) return;

   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();

   sqlcmd.Form("SELECT * FROM %s%s%s WHERE %s%s%s = %d ORDER BY %s%s%s",
                quote, sqlio::IdsTable, quote,
                quote, sqlio::IT_Type, quote, TSQLStructure::kIdTable,
                quote, sqlio::IT_TableID, quote);

   TSQLResult* res = SQLQuery(sqlcmd.Data(), 1);

   TSQLRow* row = 0;

   if (res!=0)
      while ((row = res->Next())!=0) {
         Long64_t tableid = sqlio::atol64(row->GetField(0));
         Int_t version = atoi(row->GetField(1));

         const char* classname = row->GetField(3);
         const char* classtable = row->GetField(4);

         TSQLClassInfo* info = new TSQLClassInfo(tableid, classname, version);
         info->SetClassTableName(classtable);

         if (fSQLClassInfos==0) fSQLClassInfos = new TList;
         fSQLClassInfos->Add(info);

         delete row;
      }
   delete res;


   TIter next(fSQLClassInfos);
   TSQLClassInfo* info = 0;

   while ((info = (TSQLClassInfo*) next()) != 0) {
      sqlcmd.Form("SELECT * FROM %s%s%s WHERE %s%s%s = %lld ORDER BY %s%s%s",
                   quote, sqlio::IdsTable, quote,
                   quote, sqlio::IT_TableID, quote, info->GetClassId(),
                   quote, sqlio::IT_SubID, quote);
      res = SQLQuery(sqlcmd.Data(), 1);

      TObjArray* cols = 0;

      if (res!=0)
         while ((row = res->Next())!=0) {

            Int_t typ = atoi(row->GetField(2));

            const char* fullname = row->GetField(3);
            const char* sqlname = row->GetField(4);
            const char* info2 = row->GetField(5);

            if (typ==TSQLStructure::kIdColumn) {
                if (cols==0) cols = new TObjArray;
                cols->Add(new TSQLClassColumnInfo(fullname, sqlname, info2));
            }

            delete row;
         }

      delete res;

      info->SetColumns(cols);
   }

   sqlcmd.Form("SELECT * FROM %s%s%s WHERE %s%s%s = %d ORDER BY %s%s%s",
                quote, sqlio::IdsTable, quote,
                quote, sqlio::IT_Type, quote, TSQLStructure::kIdRawTable,
                quote, sqlio::IT_TableID, quote);

   res = SQLQuery(sqlcmd.Data(), 1);

   if (res!=0)
      while ((row = res->Next())!=0) {
         Long64_t tableid = sqlio::atol64(row->GetField(0));
         Int_t version = atoi(row->GetField(1));

         const char* classname = row->GetField(3);
         const char* rawtable = row->GetField(4);

         TSQLClassInfo* info2 = FindSQLClassInfo(classname, version);

         if (info2==0) {
            info2 = new TSQLClassInfo(tableid, classname, version);

            if (fSQLClassInfos==0) fSQLClassInfos = new TList;
            fSQLClassInfos->Add(info2);
         }

         info2->SetRawTableName(rawtable);
         info2->SetRawExist(kTRUE);

         delete row;
      }

   delete res;
}


////////////////////////////////////////////////////////////////////////////////
/// Add entry into IdsTable, where all tables names and columns names are listed

void TSQLFile::AddIdEntry(Long64_t tableid, Int_t subid, Int_t type,
                          const char* name, const char* sqlname, const char* info)
{
   if ((fSQL==0) || !IsWritable()) return;

   TString sqlcmd;
   const char* valuequote = SQLValueQuote();
   const char* quote = SQLIdentifierQuote();

   if (!fIdsTableExists) {

      if (SQLTestTable(sqlio::IdsTable)) {
         sqlcmd.Form("DROP TABLE %s%s%s", quote, sqlio::IdsTable, quote);
         SQLQuery(sqlcmd.Data());
      }

      sqlcmd.Form("CREATE TABLE %s%s%s (%s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s)",
                  quote, sqlio::IdsTable, quote,
                  quote, sqlio::IT_TableID, quote, SQLIntType(),
                  quote, sqlio::IT_SubID, quote, SQLIntType(),
                  quote, sqlio::IT_Type, quote, SQLIntType(),
                  quote, sqlio::IT_FullName, quote, SQLSmallTextType(),
                  quote, sqlio::IT_SQLName, quote, SQLSmallTextType(),
                  quote, sqlio::IT_Info, quote, SQLSmallTextType());
      if ((fTablesType.Length()>0) && IsMySQL()) {
         sqlcmd +=" ENGINE=";
         sqlcmd += fTablesType;
      }
      SQLQuery(sqlcmd.Data());

      fIdsTableExists = kTRUE;
   }

   sqlcmd.Form("INSERT INTO %s%s%s VALUES (%lld, %d, %d, %s%s%s, %s%s%s, %s%s%s)",
               quote, sqlio::IdsTable, quote,
               tableid, subid, type,
               valuequote, name, valuequote,
               valuequote, sqlname, valuequote,
               valuequote, info, valuequote);

   SQLQuery(sqlcmd.Data());
}

////////////////////////////////////////////////////////////////////////////////
/// Create normal class table if required

Bool_t TSQLFile::CreateClassTable(TSQLClassInfo* sqlinfo, TObjArray* colinfos)
{
   if (sqlinfo==0) return kFALSE;

   // this is normal situation, when no extra column infos was created when not necessary
   if (colinfos==0) return sqlinfo->IsClassTableExist();

   if (sqlinfo->IsClassTableExist()) {
      if (colinfos!=0) {
         colinfos->Delete();
         delete colinfos;
         //Error("CreateClassTable","Why colinfos for table %s", sqlinfo->GetClassTableName());
      }
      return kTRUE;
   }

   if (gDebug>2)
      Info("CreateClassTable", "cl:%s", sqlinfo->GetName());

   const char* quote = SQLIdentifierQuote();

   AddIdEntry(sqlinfo->GetClassId(),
              sqlinfo->GetClassVersion(),
              TSQLStructure::kIdTable,
              sqlinfo->GetName(),
              sqlinfo->GetClassTableName(),
              "Main class table");

   TString sqlcmd;
   sqlcmd.Form("CREATE TABLE %s%s%s (",
                quote, sqlinfo->GetClassTableName(), quote);

   TIter iter(colinfos);
   TSQLClassColumnInfo* col;
   Bool_t first = kTRUE;
   Bool_t forcequote = IsOracle();
   Int_t colid = 0;
   while ((col=(TSQLClassColumnInfo*)iter())!=0) {
      if (!first) sqlcmd+=", "; else first = false;

      const char* colname = col->GetSQLName();
      if ((strpbrk(colname,"[:.]<>")!=0) || forcequote) {
         sqlcmd += quote;
         sqlcmd += colname;
         sqlcmd += quote;
         sqlcmd += " ";
      } else {
         sqlcmd += colname,
         sqlcmd += " ";
      }

      sqlcmd += col->GetSQLType();

      AddIdEntry(sqlinfo->GetClassId(),
                 colid++,
                 TSQLStructure::kIdColumn,
                 col->GetName(),
                 col->GetSQLName(),
                 col->GetSQLType());
   }
   sqlcmd += ")";

   if ((fTablesType.Length()>0)  && IsMySQL()) {
      sqlcmd +=" ENGINE=";
      sqlcmd += fTablesType;
   }

   SQLQuery(sqlcmd.Data());

   sqlinfo->SetColumns(colinfos);

   if (GetUseIndexes()>kIndexesBasic) {

      TString indxname = sqlinfo->GetClassTableName();
      indxname.ReplaceAll("_ver","_i1x");

      sqlcmd.Form("CREATE UNIQUE INDEX %s%s_I1%s ON %s%s%s (%s%s%s)",
                  quote, indxname.Data(), quote,
                  quote, sqlinfo->GetClassTableName(), quote,
                  quote, SQLObjectIdColumn(), quote);
      SQLQuery(sqlcmd.Data());
   }

   return kTRUE;
}

////////////////////////////////////////////////////////////////////////////////
/// Create the raw table

Bool_t TSQLFile::CreateRawTable(TSQLClassInfo* sqlinfo)
{
   if (sqlinfo==0) return kFALSE;

   if (sqlinfo->IsRawTableExist()) return kTRUE;

   const char* quote = SQLIdentifierQuote();

   if (gDebug>2)
      Info("CreateRawTable", "%s", sqlinfo->GetName());

   TString sqlcmd;

   sqlcmd.Form("CREATE TABLE %s%s%s (%s%s%s %s, %s%s%s %s, %s %s, %s %s)",
               quote, sqlinfo->GetRawTableName(), quote,
               quote, SQLObjectIdColumn(), quote, SQLIntType(),
               quote, SQLRawIdColumn(), quote, SQLIntType(),
               sqlio::BT_Field, SQLSmallTextType(),
               sqlio::BT_Value, SQLSmallTextType());

   if ((fTablesType.Length()>0) && IsMySQL()) {
      sqlcmd +=" ENGINE=";
      sqlcmd += fTablesType;
   }

   SQLQuery(sqlcmd.Data());
   sqlinfo->SetRawExist(kTRUE);

   if (GetUseIndexes()>kIndexesClass) {
      TString indxname = sqlinfo->GetClassTableName();
      indxname.ReplaceAll("_ver","_i2x");

      sqlcmd.Form("CREATE UNIQUE INDEX %s%s_I2%s ON %s%s%s (%s%s%s, %s%s%s)",
                  quote, indxname.Data(), quote,
                  quote, sqlinfo->GetRawTableName(), quote,
                  quote, SQLObjectIdColumn(), quote,
                  quote, SQLRawIdColumn(), quote);
      SQLQuery(sqlcmd.Data());
   }

   AddIdEntry(sqlinfo->GetClassId(),
              sqlinfo->GetClassVersion(),
              TSQLStructure::kIdRawTable,
              sqlinfo->GetName(),
              sqlinfo->GetRawTableName(),
              "Raw data class table");

   return kTRUE;
}

////////////////////////////////////////////////////////////////////////////////
/// Checks that table for big strings is exists
/// If not, will be created

Bool_t TSQLFile::VerifyLongStringTable()
{
   if (fSQL==0) return kFALSE;

   if (SQLTestTable(sqlio::StringsTable)) return kTRUE;

   const char* quote = SQLIdentifierQuote();

   TString sqlcmd;
   sqlcmd.Form("CREATE TABLE %s (%s%s%s %s, %s%s%s %s, %s %s)",
               sqlio::StringsTable,
               quote, SQLObjectIdColumn(), quote, SQLIntType(),
               quote, SQLStrIdColumn(), quote, SQLIntType(),
               sqlio::ST_Value, SQLBigTextType());

   if (fTablesType.Length()>0) {
      sqlcmd +=" ENGINE=";
      sqlcmd += fTablesType;
   }

   SQLQuery(sqlcmd.Data());

   return kTRUE;
}

////////////////////////////////////////////////////////////////////////////////
/// Produces id which will be placed in column instead of string itself

TString TSQLFile::CodeLongString(Long64_t objid, Int_t strid)
{
   TString res;
   res.Form("%s %lld %s %d %s", sqlio::LongStrPrefix, objid, sqlio::LongStrPrefix, strid, sqlio::LongStrPrefix);
   return res;
}

////////////////////////////////////////////////////////////////////////////////
/// Checks if this is long string code
/// returns 0, if not or string id

Int_t TSQLFile::IsLongStringCode(Long64_t objid, const char* value)
{
   if (value==0) return 0;
   if (strlen(value)<strlen(sqlio::LongStrPrefix)*3+6) return 0;
   if (strstr(value, sqlio::LongStrPrefix)!=value) return 0;

   value+=strlen(sqlio::LongStrPrefix);
   if (*value++!=' ') return 0;
   TString s_strid, s_objid;
   if ((*value<'1') || (*value>'9')) return 0;
   do {
      s_objid.Append(*value++);
   } while ((*value!=0) && (*value>='0') && (*value<='9'));

   if (*value++ != ' ') return 0;
   if ((*value==0) || (strstr(value, sqlio::LongStrPrefix)!=value)) return 0;
   value+=strlen(sqlio::LongStrPrefix);
   if (*value++!=' ') return 0;

   if ((*value<'1') || (*value>'9')) return 0;
   do {
      s_strid.Append(*value++);
   } while ((*value!=0) && (*value>='0') && (*value<='9'));
   if (*value++!=' ') return 0;

   if ((*value==0) || (strcmp(value, sqlio::LongStrPrefix)!=0)) return 0;

   Long64_t objid2 = sqlio::atol64(s_objid.Data());
   if (objid2!=objid) return 0;

   return atoi(s_strid.Data());
}

////////////////////////////////////////////////////////////////////////////////
/// Returns value of string, extracted from special table,
/// where long strings are stored

Bool_t TSQLFile::GetLongString(Long64_t objid, Int_t strid, TString& value)
{
   if (!SQLTestTable(sqlio::StringsTable)) return kFALSE;

   TString cmd;
   const char* quote = SQLIdentifierQuote();
   cmd.Form("SELECT %s FROM %s%s%s WHERE %s%s%s=%lld AND %s%s%s=%d",
            sqlio::ST_Value,
            quote, sqlio::StringsTable, quote,
            quote, SQLObjectIdColumn(), quote, objid,
            quote, SQLStrIdColumn(), quote, strid);

   TSQLResult* res = SQLQuery(cmd.Data(), 1);
   if (res==0) return kFALSE;
   TSQLRow* row = res->Next();
   if (row==0) { delete res; return kFALSE; }
   value = row->GetField(0);

   delete row;
   delete res;

   return kTRUE;
}

////////////////////////////////////////////////////////////////////////////////
/// Checks that objects table is exists
/// If not, table will be created
/// Returns maximum value for existing objects id

Long64_t TSQLFile::VerifyObjectTable()
{
   if (fSQL==0) return -1;

   Long64_t maxid = -1;

   if (gDebug>2)
      Info("VerifyObjectTable", "Checks if object table is there");

   if (SQLTestTable(sqlio::ObjectsTable))
      maxid = SQLMaximumValue(sqlio::ObjectsTable, SQLObjectIdColumn());
   else {
      TString sqlcmd;
      const char* quote = SQLIdentifierQuote();
      sqlcmd.Form("CREATE TABLE %s%s%s (%s%s%s %s, %s%s%s %s, %s%s%s %s, %s%s%s %s)",
                  quote, sqlio::ObjectsTable, quote,
                  quote, SQLKeyIdColumn(), quote, SQLIntType(),
                  quote, SQLObjectIdColumn(), quote, SQLIntType(),
                  quote, sqlio::OT_Class, quote, SQLSmallTextType(),
                  quote, sqlio::OT_Version, quote, SQLIntType());

      if ((fTablesType.Length()>0) && IsMySQL()) {
         sqlcmd +=" ENGINE=";
         sqlcmd += fTablesType;
      }

      SQLQuery(sqlcmd.Data());

      if (GetUseIndexes()>kIndexesNone) {
         sqlcmd.Form("CREATE UNIQUE INDEX %s%s%s ON %s%s%s (%s%s%s)",
                      quote, sqlio::ObjectsTableIndex, quote,
                      quote, sqlio::ObjectsTable, quote,
                      quote, SQLObjectIdColumn(), quote);
         SQLQuery(sqlcmd.Data());
      }
   }

   return maxid;
}

////////////////////////////////////////////////////////////////////////////////
/// Read from objects table data for specified objectid

Bool_t TSQLFile::SQLObjectInfo(Long64_t objid, TString& clname, Version_t &version)
{
   if (fSQL==0) return kFALSE;

   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();
   sqlcmd.Form("SELECT %s%s%s, %s%s%s FROM %s%s%s WHERE %s%s%s=%lld",
               quote, sqlio::OT_Class, quote,
               quote, sqlio::OT_Version, quote,
               quote, sqlio::ObjectsTable, quote,
               quote, SQLObjectIdColumn(), quote, objid);
   TSQLResult* res = SQLQuery(sqlcmd.Data(), 1);
   if (res==0) return kFALSE;
   TSQLRow* row = res->Next();
   if (row!=0) {
      clname = row->GetField(0);
      version = atoi(row->GetField(1));
   }

   delete row;
   delete res;
   return row!=0;
}

////////////////////////////////////////////////////////////////////////////////
/// Produce array of TSQLObjectInfo objects for all objects, belong to that key
/// Array should be deleted by calling function afterwards

TObjArray* TSQLFile::SQLObjectsInfo(Long64_t keyid)
{
   if (fSQL==0) return 0;

   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();
   sqlcmd.Form("SELECT %s%s%s, %s%s%s, %s%s%s FROM %s%s%s WHERE %s%s%s=%lld ORDER BY %s%s%s",
               quote, SQLObjectIdColumn(), quote,
               quote, sqlio::OT_Class, quote,
               quote, sqlio::OT_Version, quote,
               quote, sqlio::ObjectsTable, quote,
               quote, SQLKeyIdColumn(), quote, keyid,
               quote, SQLObjectIdColumn(), quote);

   TObjArray* arr = 0;

   if (fLogFile!=0)
      *fLogFile << sqlcmd << std::endl;
   if (gDebug>2) Info("SQLObjectsInfo", "%s", sqlcmd.Data());
   fQuerisCounter++;

   TSQLStatement* stmt = SQLStatement(sqlcmd.Data(), 1000);

   if (stmt!=0) {
      stmt->Process();
      stmt->StoreResult();

      while (stmt->NextResultRow()) {
         Long64_t objid = stmt->GetLong64(0);
         const char* clname = stmt->GetString(1);
         Int_t version = stmt->GetInt(2);

         TSQLObjectInfo* info = new TSQLObjectInfo(objid, clname, version);
         if (arr==0) arr = new TObjArray();
         arr->Add(info);
      }

      delete stmt;
      return arr;
   }

   TSQLResult* res = SQLQuery(sqlcmd.Data(), 1);
   if (res==0) return 0;

   TSQLRow* row = 0;
   while ((row = res->Next()) != 0) {
      Long64_t objid = atoi(row->GetField(0));
      const char* clname = row->GetField(1);
      Int_t version = atoi(row->GetField(2));

      TSQLObjectInfo* info = new TSQLObjectInfo(objid, clname, version);
      if (arr==0) arr = new TObjArray();
      arr->Add(info);

      delete row;
   }
   delete res;
   return arr;
}

////////////////////////////////////////////////////////////////////////////////
/// Method return request result for specified objid from normal classtable

TSQLResult* TSQLFile::GetNormalClassData(Long64_t objid, TSQLClassInfo* sqlinfo)
{
   if (!sqlinfo->IsClassTableExist()) return 0;
   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();
   sqlcmd.Form("SELECT * FROM %s%s%s WHERE %s%s%s=%lld",
               quote, sqlinfo->GetClassTableName(), quote,
               quote, SQLObjectIdColumn(), quote, objid);
   return SQLQuery(sqlcmd.Data(), 2);
}

////////////////////////////////////////////////////////////////////////////////
/// Return data for several objects from the range from normal class table

TSQLResult* TSQLFile::GetNormalClassDataAll(Long64_t minobjid, Long64_t maxobjid, TSQLClassInfo* sqlinfo)
{
   if (!sqlinfo->IsClassTableExist()) return 0;
   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();
   sqlcmd.Form("SELECT * FROM %s%s%s WHERE %s%s%s BETWEEN %lld AND %lld ORDER BY %s%s%s",
               quote, sqlinfo->GetClassTableName(), quote,
               quote, SQLObjectIdColumn(), quote, minobjid, maxobjid,
               quote, SQLObjectIdColumn(), quote);
   return SQLQuery(sqlcmd.Data(), 2);
}

////////////////////////////////////////////////////////////////////////////////
/// Method return request results for specified objid from _streamer_ classtable

TSQLResult* TSQLFile::GetBlobClassData(Long64_t objid, TSQLClassInfo* sqlinfo)
{
   if (!sqlinfo->IsRawTableExist()) return 0;
   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();
   sqlcmd.Form("SELECT %s, %s FROM %s%s%s WHERE %s%s%s=%lld ORDER BY %s%s%s",
               sqlio::BT_Field, sqlio::BT_Value,
               quote, sqlinfo->GetRawTableName(), quote,
               quote, SQLObjectIdColumn(), quote, objid,
               quote, SQLRawIdColumn(), quote);
   return SQLQuery(sqlcmd.Data(), 2);
}

////////////////////////////////////////////////////////////////////////////////
/// Method return request results for specified objid from _streamer_ classtable
/// Data returned in form of statement, where direct access to values are possible

TSQLStatement* TSQLFile::GetBlobClassDataStmt(Long64_t objid, TSQLClassInfo* sqlinfo)
{
   if (!sqlinfo->IsRawTableExist()) return 0;

   TString sqlcmd;
   const char* quote = SQLIdentifierQuote();
   sqlcmd.Form("SELECT %s, %s FROM %s%s%s WHERE %s%s%s=%lld ORDER BY %s%s%s",
               sqlio::BT_Field, sqlio::BT_Value,
               quote, sqlinfo->GetRawTableName(), quote,
               quote, SQLObjectIdColumn(), quote, objid,
               quote, SQLRawIdColumn(), quote);

   if (fLogFile!=0)
      *fLogFile << sqlcmd << std::endl;
   if (gDebug>2) Info("BuildStatement", "%s", sqlcmd.Data());
   fQuerisCounter++;

   TSQLStatement* stmt = SQLStatement(sqlcmd.Data(), 1000);
   if (stmt==0) return 0;

   stmt->Process();

   stmt->StoreResult();

   return stmt;
}

////////////////////////////////////////////////////////////////////////////////
/// Store object in database. Return stored object id or -1 if error

Long64_t TSQLFile::StoreObjectInTables(Long64_t keyid, const void* obj, const TClass* cl)
{
   if (fSQL==0) return -1;

   Long64_t objid = VerifyObjectTable();
   if (objid<=0) objid = 1; else objid++;

   TBufferSQL2 buffer(TBuffer::kWrite, this);

   TSQLStructure* s = buffer.SqlWriteAny(obj, cl, objid);

   if ((buffer.GetErrorFlag()>0) && s) {
      Error("StoreObjectInTables","Cannot convert object data to TSQLStructure");
      objid = -1;
   } else {
      TObjArray cmds;
      // here tables may be already created, therefore
      // it should be protected by transactions operations
      if (s && !s->ConvertToTables(this, keyid, &cmds)) {
         Error("StoreObjectInTables","Cannot convert to SQL statements");
         objid = -1;
      } else {
         Bool_t needcommit = kFALSE;

         if (GetUseTransactions()==kTransactionsAuto) {
            SQLStartTransaction();
            needcommit = kTRUE;
         }

         if (!SQLApplyCommands(&cmds)) {
            Error("StoreObject","Cannot correctly store object data in database");
            objid = -1;
            if (needcommit) SQLRollback();
         } else {
            if (needcommit) SQLCommit();
         }
      }
      cmds.Delete();
   }

   return objid;
}

////////////////////////////////////////////////////////////////////////////////
/// Returns sql type name which is most closer to ROOT basic type.
/// typ should be from TVirtualStreamerInfo:: constansts like TVirtualStreamerInfo::kInt

const char* TSQLFile::SQLCompatibleType(Int_t typ) const
{
   return (typ<0) || (typ>18) ? 0 : fBasicTypes[typ];
}

////////////////////////////////////////////////////////////////////////////////
/// return SQL integer type

const char* TSQLFile::SQLIntType() const
{
   return SQLCompatibleType(TVirtualStreamerInfo::kInt);
}

////////////////////////////////////////////////////////////////////////////////
/// Create entry for directory in database

Long64_t TSQLFile::DirCreateEntry(TDirectory* dir)
{
   TDirectory* mother = dir->GetMotherDir();
   if (mother==0) mother = this;

   // key will be added to mother directory
   TKeySQL* key = new TKeySQL(mother, dir, dir->GetName(), dir->GetTitle());

   return key->GetDBKeyId();
}

////////////////////////////////////////////////////////////////////////////////
/// Read directory list of keys from database

Int_t TSQLFile::DirReadKeys(TDirectory* dir)
{
   // First delete all old keys
   dir->GetListOfKeys()->Delete();

   if (gDebug>2)
      Info("DirReadKeys","dir = %s id = %lld", dir->GetName(), dir->GetSeekDir());

   return StreamKeysForDirectory(dir, kFALSE);
}

////////////////////////////////////////////////////////////////////////////////
/// Write directory keys list to database

void TSQLFile::DirWriteKeys(TDirectory* dir)
{
   StreamKeysForDirectory(dir, kTRUE);
}

////////////////////////////////////////////////////////////////////////////////
/// Update dir header in the file

void TSQLFile::DirWriteHeader(TDirectory* dir)
{
   TSQLClassInfo* sqlinfo = FindSQLClassInfo("TDirectory",TDirectoryFile::Class()->GetClassVersion());
   if (sqlinfo==0) return;

   // try to identify key with data for our directory
   TKeySQL* key = FindSQLKey(dir->GetMotherDir(), dir->GetSeekDir());
   if (key==0) return;

   const char* valuequote = SQLValueQuote();
   const char* quote = SQLIdentifierQuote();

   TString timeC = fDatimeC.AsSQLString();
   TSQLStructure::AddStrBrackets(timeC, valuequote);

   TString timeM = fDatimeM.AsSQLString();
   TSQLStructure::AddStrBrackets(timeM, valuequote);

   TString uuid = dir->GetUUID().AsString();
   TSQLStructure::AddStrBrackets(uuid, valuequote);

   TString sqlcmd;

   TString col1name = "CreateTime";
   TString col2name = "ModifyTime";
   TString col3name = "UUID";
   if (GetUseSuffixes()) {
      col1name+=sqlio::StrSuffix;
      col2name+=sqlio::StrSuffix;
      col3name+=sqlio::StrSuffix;
   }

   sqlcmd.Form("UPDATE %s%s%s SET %s%s%s=%s, %s%s%s=%s, %s%s%s=%s WHERE %s%s%s=%lld",
                quote, sqlinfo->GetClassTableName(), quote,
                quote, col1name.Data(), quote, timeC.Data(),
                quote, col2name.Data(), quote, timeM.Data(),
                quote, col3name.Data(), quote, uuid.Data(),
                quote, SQLObjectIdColumn(), quote, key->GetDBObjId());

   SQLQuery(sqlcmd.Data());
}

////////////////////////////////////////////////////////////////////////////////
/// Streamer for TSQLFile class.
/// Stores only data for TDirectory.

void TSQLFile::Streamer(TBuffer &b)
{

   TString sbuf;

   if (b.IsReading()) {
      Version_t R__v = b.ReadVersion(0, 0);
      b.ClassBegin(TSQLFile::Class(), R__v);

      b.ClassMember("CreateTime","TString");
      sbuf.Streamer(b);
      TDatime timeC(sbuf.Data());
      fDatimeC = timeC;

      b.ClassMember("ModifyTime","TString");
      sbuf.Streamer(b);
      TDatime timeM(sbuf.Data());
      fDatimeM = timeM;

      b.ClassMember("UUID","TString");
      sbuf.Streamer(b);
      TUUID id(sbuf.Data());
      fUUID = id;

      b.ClassEnd(TSQLFile::Class());
   } else {

      b.WriteVersion(TSQLFile::Class());

      b.ClassBegin(TSQLFile::Class());

      b.ClassMember("CreateTime","TString");
      sbuf = fDatimeC.AsSQLString();
      sbuf.Streamer(b);

      b.ClassMember("ModifyTime","TString");
      fDatimeM.Set();
      sbuf = fDatimeM.AsSQLString();
      sbuf.Streamer(b);

      b.ClassMember("UUID","TString");
      sbuf = fUUID.AsString();
      sbuf.Streamer(b);

      b.ClassEnd(TSQLFile::Class());
   }
}