NOT NULL Constraint

• NOT NULL  constraint is use to restrict the the NULL value in Database.
• NOT NULL should be define only at column level.
• NOT NULL constraints are the only constraints you can specify inline on XMLType and VARRAY columns.
• Every row in the table must contain a value for the column it validated by the NOT NULL constraint

Restrictions :

• NULL or NOT NULL can't be specify in a view constraint.
• NULL or NOT NULL can't specify for an attribute which use a CHECK constraint with the IS [NOT] NULL condition.

Syntax :

CREATE TABLE <TABLE_NAME>
(COL_NAME1 <DATA_TYPE> (WIDTH) NOT NULL,
 COL_NAME2  <DATA_TYPE> (WIDTH) CONSTRAINT CONS_NAME NOT NULL,
 COL_NAMEn   <DATA_TYPE> (WIDTH));

See The Example:

NOT NULL CONSTRAINT EXAMPLE