Integrity constraints are the rules ,regulations and restriction apllied on database to maintain integrity in the relational model (rdbms).

Here are the 5 integrity constraints in relation model:

Entity integrity constraint

Primary key cznnot have null values, if primary key is composite thenone or all of its attributes memeber cannot have null values.

Referential integrity constraint

Foreign key can have null values but if calues exists then it should matchwith the values of reference tabke (home table) and it is imposed by dbms.

Not null

Not null ensures that value of an attribute shoukd not be null.

Default

It ensures that if value of an attribute is not entered then a default value is placed.

Domain

It ensures that value entered should match with defined domain in the relational schema.