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.
Parameter:
|
f |
A composite table file or a homo-name files group |
Return value:
Boolean
Example:
|
|
A |
|
|
1 |
=file("D:/ckv.ctx") |
There is an error about ckv.ctx in executing T.update(P:D), 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. |