On SQL Server 2008
Most relational database software allows a change in one table to trigger changes in other tables based on a foreign key relation. For example let’s say we have two tables: Users and Orders that have a foreign relation defined on the user id field.
Users Orders --------- -------- USERID ORDERID USERNAME USERID
SQL Server allows you to define cascading deletes so that when you delete an entry from the users table, all related entries in the orders table are also going to be deleted.