If the insertion violates one or more constraints, then two alternatives are available:

• Default option: - Insertion can be discarded and the reason of refusal can also be explained to the user by DBMS.
• Ask the user to resubmit, correct the data, also give the cause for rejecting the insertion.

Example:

Consider the Relation PERSON of Example :

PERSON

(1)     Insert<1, 'Vipin', 20, 'Mayur Vihar'> into PERSON

Violated constraint: - Key constraint

Reason: - Primary key 1 already exists in PERSON.

Dealing: - DBMS could ask the user to give valid PERSON_ID value and accept the insertion if valid PERSON_ID value is given.

(2)     Insert<'null', 'Anurag', 25, 'Patparganj'> into PERSON

Violated constraint: - Entity Integrity constraint

Reason: - Primary key is 'null'.

Dealing: - DBMS could ask the user to give valid PERSON_ID value and accept the insertion if valid PERSON_ID value is given.

(3)     Insert<'abc', 'Suman', 25, 'IP college'> into PERSON

Violated constraint: - Domain constraint

Reason: - value of PERSON_ID is provide a string which is not valid.

(4)     Insert <10, 'Anu', 25, 'Patpatganj'> into PERSON

Violated constraint: - None