Question

Write a short note on Primary key constraints.

Answer 1

Primary Constraint:

• Primly Constraint declares a field as a Primary key which helps to uniquely identify a recor<}ll
• Primary Constraint is similar to a unique constraint except that only one field of a table can be set as the primary key.
• The primary key does not allow NULL values and therefore a field declared as the primary key must have the NOT NULL constraint.