‹ BACK

SQL PRIMARY KEY Constraint

SQL PRIMARY KEY Constraint

The PRIMARY KEY constraint uniquely identifies each record in a database table.
Primary keys must contain UNIQUE values.
A primary key column cannot contain NULL values.
Most tables should have a primary key, and each table can have only ONE primary key.
Read more: SQL UNIQUE Constraint
NULL-values unique-key primary-key constraints

To check your knowledge the following tests are recommended:
Check your sql sql skills.