Relational Lists is very cool new feature in SharePoint 2010. Having word Relational in SharePoint 2010 now lists are full fledged relational databases. Relational lists are created using Lookup Fields. so let see in action . here are the steps to create relational list in SharePoint 2010.
1) Create a Parent Custom List.
2) Create a Child Custom List referring Lookup filed column this link will create a Projected Field against the lookup automatically .
3) Add Sample Data in both Parent and Child List.
Now Add a new column Called StateName with following settings.
Now Create a Child Custom List & Add new column called CityIn.
Enforcing Relational Behavior
1) When "Restricted Delete" option is set and if you try to delete an Item in Parent list you will get the following error and informs you that the deleting item that has related items.
2) When "Cascade Delete" option is set and if you try to delete an item you will get the following message dialog.
Deleted Item Moved to Recycle Bin.