CHECK Table Constraint
Table constraint activated when an operation to insert, update or delete records in the table is called
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.
CREATE TABLE purchase_order; (POid i PRIMARY KEY, SuppId i, POtotal n(10,2),; CHECK callauth(); ERROR "Not authorized")