Id  Name    Dept 
1   John    D1
2   Philip  D2 

Id  Name    Dept 
1   Maha    D1
2   Raj     D2 

Id   varchar2(100),
Name varchar2(100),
Dept varchar2(100),
Tab  varchar2(100) ( Here i need to give "Tab1" if its comes from file1 as same as "Tab2" if from file2)

create or replace view my_table as
select Id,Name,Dept,'TAB1' Tab 
from tab1
union all
select Id,Name,Dept,'TAB2' Tab 
from tab2;