How to enable Foreign Key Concept for a SharePoint 2010 LookUp Column

• Login to your SharePoint site with Administrator Credentials.
• Now Create a Parent List(Ex:- Employee Department).
• Now Create a Child List.
• Now Create a Lookup Column.
• Now while creating a Lookup column go to the Relationship section at the end of the page.
• Click on Enforce Relationship Behavior checkbox.
• Now click on Restrict Delete Radio Button and press ok.
• Now suppose if the data is used with in a Child site, Now if you try to delete the ListItem in the parent list then it will not get deleted and SharePoint will give you and error.