SQL/MX Quick Start (H06.04+, J06.03+)

Protecting Database Integrity

HP NonStop SQL/MX Quick Start—540438-001

8-2

Ending a Transaction

If a problem occurs during the transaction, you can roll back, or undo, the transaction

to cancel the changes you made up to that point. If no problems occur, you can commit

the changes to the database.

Example

Suppose you realize that you did not want prices between $1000 and $2000 doubled.

You can enter the ROLLBACK WORK statement to roll back all changes since you

entered BEGIN WORK:

ROLLBACK WORK;

--- SQL operation complete.

The database values are the same as they were before you entered the UPDATE

statement.

Example

Now you can start another transaction and enter the correct version of the UPDATE

statement. When you know the changes are correct, enter the COMMIT WORK

statement to complete the transaction:

COMMIT WORK;

--- SQL operation complete.

Tip

•

By default, NonStop SQL/MX automatically defines a transaction for SELECT,

DELETE, UPDATE, and INSERT statements that you enter. This default protects

the database if system failure or some other system problem occurs. If no

problems occur, NonStop SQL/MX commits the changes to the database, and you

cannot roll back the changes.

•

Only audited tables are protected by transactions. By default, tables are audited,

and you can protect your transactions on tables by using BEGIN WORK, COMMIT

WORK, and ROLLBACK WORK.