ROLLBACK Command Example

In the following example, the customer table in the testdata database is opened. Optimistic table buffering is set for the customer table. The contents of the cust_id and company fields are displayed, and then the contents of the company field is replaced within the buffered data.

BEGIN TRANSACTION is issued to start a transaction. A TABLEUPDATE is used to write the changes to the table. The new contents are displayed, and ROLLBACK is issued to restore the original contents of the company field. The cust_id and company fields are displayed again with the company field containing its original values.

CLOSE DATABASES
CLEAR

* Transactions are only supported within a DBC
OPEN DATABASE (HOME(2) + 'Data\testdata')

SET MULTILOCKS ON      && Required for buffering

USE customer
=CURSORSETPROP("Buffering",5)
? 'The original company field'
LIST FIELDS cust_id, company NEXT 5
REPLACE ALL company WITH "***" && Change field contents

BEGIN TRANSACTION
   =TABLEUPDATE(.T.)
   GO TOP
   ? 'The modified company field'
   LIST FIELDS cust_id, company NEXT 5
ROLLBACK           && Restore original field contents

=TABLEREVERT(.T.)
GO TOP
? 'The restored company field'
LIST FIELDS cust_id, company NEXT 5