Difference between revisions of "CHECK Table Constraint"

Revision as of 16:22, 9 December 2009

Purpose

Table constraint activated when an operation to insert, update or delete records in the table is called

Syntax

CHECK <condition>

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 CHECK table constraint is activated when an operation to insert, update or delete records in the table is called. The <condition> specified must evaluate to True (.T.) for the operation to succeed. If the <condition> evaluates to False (.F.) the operation is abandoned and the ERROR table constraint message is displayed. If the ERROR table constraint has not been defined, a default error message is displayed.

Example

set sql to vfp
CREATE TABLE purchase_order (POid i PRIMARY KEY, SuppId i, POtotal n(10,2), ;
CHECK callauth() ERROR [Not authorized])

Products

Recital, Recital Server