SQL Constraints

Purpose

To define rules that help to provide data integrity

See Also

ALTER TABLE, CREATE TABLE, GRANT, REVOKE

Description

A constraint is used to define rules that help to provide data integrity. There are two different types of constraints, TABLE constraints, which do not require any column information and column constraints, which are specific to the column name specified. You must have ALTER privilege on the table. The table will be locked for EXCLUSIVE use during the operation.

Table Constraints

CHECK	ERROR	FOREIGN KEY
INDEX	KEY	ONAFTERDELETE
ONAFTERINSERT	ONAFTERUPDATE	ONCLOSE
ONDELETE	ONINSERT	ONOPEN
ONROLLBACK	ONUPDATE	PRIMARY KEY
UNIQUE

Column Constraints

AUTO_INCREMENT	AUTOINC	CALCULATED
CHECK	DEFAULT	DESCRIPTION
ERROR	FOREIGN KEY	NOCPTRANS
NOT NULL	NULL	PRIMARY KEY
RANGE	RECALCULATE	REFERENCES
SET CHECK	UNIQUE