Check constraint in sql

Check constraint in sql.

Check Constraint is used to check the validate data, data format etc.

For Example: 

Customer age must be greater than 18.

Customer phone number be in this format XX-XXXXXX

Check Constraint Example:

Create table NewOrder
(
CID varchar(10)not null,
Name varchar(20)not null,
Age int not null Constraint chkAge Check(Age>=18),
Address varchar(20)not null,
Phone varchar(10)Constraint chkphone check (Phone like '[0-9][0-9]-[0-9][0-9][0-9][0-9][0-9][0-9]'
)

Insert into NewOrder Values('001','Smit','18','234','23-232434')
Insert into NewOrder Values('002','Anu','18','234','01-238434')

ALTER/DROP CHECK constraint

Alter table NewOrder drop Constraint chkAge

Alter table NewOrder drop constraint chkphone

ALTER / ADD Check constraint

alter table NewOrder add Constraint chkAge check(Age>=18)

alter table NewOrder add Constraint chkphone check (Phone like '[0-9][0-9]-[0-9][0-9][0-9][0-9][0-9][0-9]')

CHECK constraint in video

CHECK constraint in Image