for all entires with join

experts, help needed

itab has following fields,

vbeln erdat erzet vkorg vtweg

kunnr posnr matnr bmeng.

i have written like this

if itab is not initial.

SELECT a_{vbeln a}erdat a_{erzet a}vkorg a~vtweg

a_{kunnr b}posnr b~matnr

FROM vbak AS a INNER JOIN vbap AS b

ON a_{vbeln = b}vbeln

INTO TABLE itab1

FOR ALL ENTRIES IN itab

WHERE a~vbeln = itab-vbeln.

endif.

i need to fetch confirm quantity from vbep ie bmeng filed for the items in vbap into table itab1.

so do i need to add this as well in the above join or seperately i need to select it after the above select query.

pls suggest the modifications in the above select query accordingly.