SAP ABAP Problems & Solution

We need to know about Self Join meaning ,then we can understand its purpose.I am giving a short meaning : Joining a table with it's self is known as self Join. We can define Self join as like :  Inner Self Join Outer Self Join (Left,Wright & Full Join) Cross Self Join Inner Self Join : Select A. Column_Name1, B.Column_Name1 from Table_name A Inner Join Table_name B On A.Primary_Table = B. Primary_Table  Outer Self Join: Select A. Column_Name1, B.Column_Name1 from Table_name A Left Join Table_name B On A.Primary_Table = B. Primary_Table Cross Self Join: Select A. Column_Name1, B.Column_Name1 from Table_name A Cross Join Table_name B