Transaction Mechanism (Magic xpa 2.x)

If the transaction does not complete successfully, a ROLLBACK statement returns the data to the state it was in prior to the beginning of the transaction. If the transaction completes successfully, a COMMIT statement permanently stores the data in the database.

Due to the nature of SQL and relational database architecture, where each update can act on only one table at a time and where there are no trailers in the usual sense, two update statements must be executed simultaneously. Both update statements must either succeed and COMMIT or fail and ROLLBACK.

In a transaction a group of updates must either COMMIT or ROLLBACK together. First a transaction is declared, and then either the COMMIT or the ROLLBACK SQL statement is issued for all the statements that have been issued since the transaction declaration.