In this post we will discuss about what is difference between primary key and foreign key in SQL server 2008.
You can see my previous posts on:
- Advantages of WCF in Asp.Net
- Read and write from Text file in Asp.Net
- Difference between Dataset and Datareader asp.net
Though primary key and foreign key looks similar but there are some difference between them.
Primary 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:
- 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 on non-clustered. You can manually create an index on foreign key.
- We can have more than one foreign key in a table.
You can see my previous posts on:
- Advantages of WCF in Asp.Net
- Read and write from Text file in Asp.Net
- Difference between Dataset and Datareader asp.net
Though primary key and foreign key looks similar but there are some difference between them.
Primary 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:
- 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 on non-clustered. You can manually create an index on foreign key.
- We can have more than one foreign key in a table.
