Code: Alles auswählen.
FIELD-SYMBOLS: <ls_itab1> LIKE LINE OF itab1,
<ls_itab2> LIKE LINE OF itab2.
LOOP AT itab1 ASSIGNING <ls_itab1>.
READ TABLE itab2 ASSIGNING <ls_itab2> WITH KEY ID = <ls_itab1>-ID.
<ls_itab1>-menge = <ls_Itab2>-menge.
ENDLOOP.