Joins on select queries.

Check this sample code

    
SELECT a~ebeln b~ebelp a~ernam a~ekgrp a~bedat 
       b~txz01 b~netwr b~afnam b~effwr
       INTO CORRESPONDING FIELDS OF TABLE it_po
       FROM ekpo AS b INNER JOIN ekko AS a
       ON b~ebeln = a~ebeln
       WHERE a~bukrs = s_bukrs  AND
             a~aedat LE p_date  AND
             a~ebeln IN s_ebeln AND
             a~bedat IN s_bedat AND
             a~ekgrp IN s_ekgrp AND
             a~frgke NE 'E'     AND
             b~loekz NOT IN ('L', 'S', 'X').

Regards

Gopi