CHECK Constraint

It defines the conditions that each row must be satisfy.CHECK constraint is used to limit the value
range that can be placed in a column.


Restrictions:

• CHECK Constraint can refer to any column in same table but it can't refer any column from other table
• In CHECK Constraint we can't use pseudo columns.
• A Single column can have multiple CHECK Constraint.
• CHECK Constraint can be define column and table level.

DEFAULT option:

• The DEFAULT option is given to maintain a default value in column.
• The DEFAULT value can be leteral or any expression or sql function.

Syntax:

CREATE TABLE <TABLE_NAME>
(COLUMN_NAME1 <DATA_TYPE>(WIDTH) CONSTRAINT Constraint_Name CHECK (column_name BETWEEN start_rng AND end_rng ) ,
 COLUMN_NAME2 <DATA_TYPE>(WIDTH) CONSTRAINT Constraint_Name CHECK (column_name=UPPER(column_name)) DISABLE,
 COLUMN_NAMEn <DATA_TYPE>(WIDTH) DEFAULT SYSDATE);


See The Example:

CHECK CONSTRAINT EXAMPLE