SQL Constraints

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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 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