Distinguish, differentiate, compare and explain what is the Difference between Primary and Foreign Key. Comparison and Differences.
Difference between Primary and Foreign Key
1. The primary key uniquely identifies a record in the table. The foreign key is a field in the table that is a primary key in another table.
2. Primary Key can’t accept null values. A foreign key can accept multiple null values.
3. By default Primary key is clustered index and data in the database table is physically organized in the sequence of a clustered index. A foreign key does not automatically create an index, clustered or non-clustered. You can manually create an index on a foreign key.
4. We can have only one Primary key in a table. We can have more than one foreign key in a table.