How to fill third internal table

Sir.

I am selecting data from two tables into two internal table but i want to creat third internal table

with LINE ITEMS.

please, tell me...

select * from vbsegs into corresponding fields of table itab_docdet where belnr in docnum and gjahr = year.

select * from vbsegk into corresponding fields of table itab_docdet1 where belnr in docnum and gjahr = year.

Manoj..