Differences between Primary key & Foreign key:
Primary Key
|
Foreign Key
|
Helps you to uniquely identify a record in the table. |
It is a field in the table that is the primary key of
another table. |
It never accepts null values. |
It may accept multiple null values. |
Primary key is a clustered index and data in the DBMS
table are physically organized in the sequence of the clustered index. |
A foreign key cannot automatically create an index,
clustered or non-clustered. However, you can manually create an index on the
foreign key. |
You can have the single Primary key in a table. |
You can have multiple foreign keys in a table. |
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