A transaction is executed entirely by using the StartTransaction, Commit, and Rollback methods of the TEDBDatabase component. A typical transaction block of code looks like this:

{
   MyDatabase->StartTransaction(EmptyEDBStringsArray);
   try
      {
      // Perform some updates to the table(s) in this database
      MyDatabase->Commit();
      }
   catch
      {
      MyDatabase->Rollback();
      throw;
      }
}

The EmptyEDBStringsArray variable is defined in the edbtype unit (Delphi or Lazarus) or edbtype header file (C++) in ElevateDB.


Restricted Transactions

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It is also possible with ElevateDB to start a restricted transaction. A restricted transaction is one that specifies only certain tables be part of the transaction. The StartTransaction method accepts an optional array of tables that can be used to specify what tables should be involved in the transaction and, subsequently, locked as part of the transaction (see below regarding locking). If this list of tables is nil (the default), then the transaction will encompass the entire database.

The following example shows how to use a restricted transaction on two tables, the Customer and Orders table:

{
   TEDBStringsArray Tables;
   Tables.Length = 2;
   Tables[1]="Customer";
   Tables[2]="Orders";
   MyDatabase->StartTransaction(Tables);
   try
      {
      // Perform some updates to the table(s) in this database
      MyDatabase->Commit();
      }
   catch
      {
      MyDatabase->Rollback();
      throw;
      }
   }
}

For more information on transactions in ElevateDB, please see the Transactions topic.