Defeine : Self Join?
Self Join is bassically use for the editing in the table itself , This is a particular case when one table joins to itself, with one or two aliases to avoid confusion. A self join can joined tables which are the same. A self join is rather unique in that it involves a relationship with only one table. For the example is when company has a hierarchal reporting structure whereby one member of staff reports to another. Self Join also use can be Outer Join or Inner Join.