ONDELETE Table Constraint

Purpose

Table constraint activated when an attempt is made to delete a record in the table

Syntax

ONDELETE <procedure>

ONBEFOREDELETE <procedure>

See Also

ALTER TABLE, CONSTRAINTS, CREATE TABLE

Description

A constraint is used to define rules that help to provide data integrity. TABLE constraints apply to table-based operations. You must have ALTER privilege on the table. The table will be locked for EXCLUSIVE use during the operation.

The ONDELETE / ONBEFOREDELETE table constraint is activated when an attempt is made to delete a record in the table. The <procedure> specified must be a character expression evaluating to a procedure name. If no file extension is included, '.prg' is assumed. The specified procedure is run before the operation to delete the record is executed and must return True (.T.) or the delete operation is cancelled.

Example

ALTER TABLE customer;
  modify ONDELETE "customer_ondelete"
ALTER TABLE customer;
  modify ONBEFOREDELETE "customer_onbeforedelete"