Delphi Application using COMMIT and ROLLBACK for Multiple SQL Updates

Question

Is it possible to use the SQL BEGIN TRANSACTION, COMMIT TRANSACTION, ROLLBACK TRANSACTION when embedding SQL Queries into an application with mutiple calls to the SQL for Table Updates. For example I have the following code:

Q.SQL.ADD(<UPDATE A RECORD>);
Q.ExecSQL;

Q.Close;
Q.SQL.Clear;
Q.SQL.ADD(<Select Some Data>);
Q.Open;

Set Some Variables

Q.Close;
Q.SQL.Clear;
Q.SQL.ADD(<UPDATE A RECORD>);
Q.ExecSQL;

What I would like to do is if the second update fails I want to roll back the first transaction.

If I set a unique notation for the BEGIN, COMMIT, ROLLBACK so as to specify what is being committed or rolled back, is it feasible.

i.e. before the first Update specify BEGIN TRANSACTION_A then after the last update specify COMMIT TRANSACTION_A

I hope that makes sense. If I was doing this in a SQL Stored Procedure then I would be able to specify this at the start and end of the procedure, but I have had to break the code down into manageable chunks due to process blocks and deadlocks on a heavy loaded SQL Server.

Answer 1

Wouldn't it be easier to use StartTransaction, Commit and Rollback on the Connection?

e.g.

Q.Connection.StartTransaction
try
    Q.SQL.ADD(); 
    Q.ExecSQL;

    Q.Close; 
    Q.SQL.Clear; 
    Q.SQL.ADD(); 
    Q.Open;

    ...


    Q.Close; 
    Q.SQL.Clear; 
    Q.SQL.ADD(); 
    Q.ExecSQL;
    Q.Connection.Commit;
except
    Q.Connection.Rollback;
end;