Difference between Primary Key & Foreign Key.
- Primary key uniquely identify a record in the table.
- Primary Key can’t accept null values.
- By default, Primary key is clustered index and data in the database table is physically organized in the sequence of clustered index.
- We can have only one Primary key in a table.
- Foreign key is a field in the table that is primary key in another table.
- Foreign key can accept multiple null value.
- Foreign key do not automatically create an index, clustered or non-clustered. You can manually create an index on foreign key.
- We can have more than one foreign key in a table.