Hi,
U Can use appending clause in Select statement like
Select data into itab1 from dbtab.
select data appending corresponding fields into itab1 from dbtab.
select data appending corresponding fields into itab1 from dbtab.
or U may Use
Loop at Itab1 into wa_tab1.
Read itab2 ....
& modify itab1
Read itab3
& modify itab1
endloop.
Regards