f.rollback()

Read(337) Label: rollback, composite table file,

Description:

Restore a composite table file to the previous state when update error happens.

Syntax:

f.rollback()

Note:

The function restores a composite table file’s entity table to the previous state when an error happens during adding, deleting, and modifying data.

Note: When error happens at the update of a composite table file, a file error prompt will appear if you use f.open() to open the composite table file. In this case rollback() is needed to do a rollback action. Different from the rollback operation on an ordinary database, there isn’t a special rollback mechanism for composite tables, users need to call f.rollback() function to to do the rollback manually.

Parameters:

f

A composite table file or a homo-name files group

Return value:

Boolean

Example:

 

A

 

1

=file("D:/ckv.ctx")

There is an eror about ckv.ctx in executing T.update(P), so error is reported when f.open() is used: Error about ckv.ctx, call f.rollback() to restore.

2

=A1.rollback()

Restore composite table file ckv.ctx to the state before update is performed