SQL Constraints- check

nThe CHECK constraint is used to limit the value range that can be placed in a column.

nIf you define a CHECK constraint on a single column it allows only certain values for this column.

Create-Check

CREATE TABLE EMPtbl1( (EMPID int NOT NULL, EMPname varchar(255) NOT NULL,
company varchar(255),salary varchar(255),City varchar(255),CONSTRAINT chk_EMPtbl1 CHECK (EMPID>0, Location=‘Bangalore’))

Alter-Check

ALTER TABLE EMPtbl1

ADD CONSTRAINT Chk_EMPtbl1 CHECK (EMPID>0, Location=‘Bangalore’))

Drop-Check

ALTER TABLE EMPtbl1

DROP CONSTRAINT chk_EMPtbl1