sqltables.C File Reference

Detailed Description

This is an example illustrating how the TSQLFile class can be used.

Histogram, list of TBox and clones array of TBox objects are stored to TSQLFile and read back. Except for the specific TSQLFile configuration, the TSQLFile functionality is absolutely similar to a normal root TFile

// example configuration for MySQL 4.1
const char* dbname = "mysql://host.domain/test";
const char* username = "user";
const char* userpass = "pass";

// example configuration for Oracle 9i
//const char* dbname = "oracle://host.domain/db-test";
//const char* username = "user";
//const char* userpass = "pass";


void sqltables()
{
   tables_write();
   tables_read();
}

void tables_write()
{
   // first connect to data base
   // "recreate" option delete all your tables !!!!
   TSQLFile* f = new TSQLFile(dbname, "recreate", username, userpass);
   if (f->IsZombie()) { delete f; return; }

   // you can change configuration only until first object
   // is written to TSQLFile
   f->SetUseSuffixes(kFALSE);
   f->SetArrayLimit(1000);
   f->SetUseIndexes(1);
//   f->SetTablesType("ISAM");
//   f->SetUseTransactions(kFALSE);

   // lets first write histogram
   TH1I* h1 = new TH1I("histo1","histo title", 1000, -4., 4.);
   h1->FillRandom("gaus",10000);
   h1->Write("histo");
   h1->SetDirectory(0);

   // here we create list of objects and store them as single key
   // without kSingleKey all TBox objects will appear as separate keys
   TList* arr = new TList;
   for(Int_t n=0;n<10;n++) {
      TBox* b = new TBox(n*10,n*100,n*20,n*200);
      arr->Add(b, Form("option_%d_option",n));
   }
   arr->Write("list",TObject::kSingleKey);

   // clones array is also stored as single key
   TClonesArray clones("TBox",10);
   for(int n=0;n<10;n++)
       new (clones[n]) TBox(n*10,n*100,n*20,n*200);
   clones.Write("clones",TObject::kSingleKey);

   // close connection to database
   delete f;
}


void tables_read()
{
   // now open connection to database for read-only
   TSQLFile* f = new TSQLFile(dbname, "open", username, userpass);
   if (f->IsZombie()) { delete f; return; }

   // see list of keys
   f->ls();

   // get histogram from DB and draw it
   TH1* h1 = (TH1*) f->Get("histo");
   if (h1!=0) {
       h1->SetDirectory(0);
       h1->Draw();
   }

   // get TList with other objects
   TObject* obj = f->Get("list");
   cout << "Printout of TList object" << endl;
   if (obj!=0) obj->Print("*");
   delete obj;

   // and get TClonesArray
   obj = f->Get("clones");
   cout << "Printout of TClonesArray object" << endl;
   if (obj!=0) obj->Print("*");
   delete obj;

   // this is query to select data of hole class from different tables
   cout << "================ TBox QUERY ================ " << endl;
   cout << f->MakeSelectQuery(TBox::Class()) << endl;
   cout << "================ END of TBox QUERY ================ " << endl;

   cout << "================== TH1I QUERY ================ " << endl;
   cout << f->MakeSelectQuery(TH1I::Class()) << endl;
   cout << "================ END of TH1I QUERY ================ " << endl;

   // close connection to database
   delete f;
}

Author

Sergey Linev

Definition in file sqltables.C.