Transaction basics

A successful CONNECT starts a transaction, and a DISCONNECT terminates the transaction. All SQL statements that execute between the CONNECT and the DISCONNECT occur within the transaction.

Before you issue a CONNECT statement, the Transaction object must exist and you must assign values to all Transaction object properties required to connect to your DBMS.

When a COMMIT executes, all changes to the database since the start of the current transaction (or since the last COMMIT or ROLLBACK) are made permanent, and a new transaction is started. When a ROLLBACK executes, all changes since the start of the current transaction are undone and a new transaction is started.

You can issue a COMMIT or ROLLBACK only if the AutoCommit property of the Transaction object is set to False (the default) and you have not already started a transaction using embedded SQL.

To optimize database processing, you can code your PowerBuilder application to take advantage of transaction pooling.

Components that you develop in PowerBuilder can participate in transactions in EAServer or other application servers. You can mark components to indicate that they will provide transaction support. When a component provides transaction support, the transaction server ensures that the component’s database operations execute as part of a transaction and that the database changes performed by the participating components are all committed or rolled back. By defining components to use transactions, you can ensure that all work performed by components that participate in a transaction occurs as intended.

PowerBuilder provides a transaction service context object called TransactionServer that gives you access to the transaction state primitives that influence whether the transaction server commits or aborts the current transaction. COM+ clients can also use the OleTxnObject object to control transactions. If you use the TransactionServer context object and set the UseContextObject DBParm parameter to Yes, COMMIT and ROLLBACK statements called in the Transaction object will result in a database error.

By default, the TransactionServer context object is not used. Instead you can use COMMIT and ROLLBACK statements to manage transactions. In this case, COMMIT is interpreted as a SetComplete function and ROLLBACK is interpreted as a SetAbort function.