How to write select within select in ABAP

Question

Hi Guys
I want to write a select statement in ABAP to select from 2 tables below is my code I want to write select within select statment in --->A and replace with ---> B
FORM sales_production_order  USING    p_vbeln TYPE vbeln_va
                             CHANGING p_aufnr TYPE aufnr
                                      p_rtcod TYPE sysubrc.
  CLEAR: p_rtcod,
         p_aufnr.
A *******
  SELECT aufnr FROM aufk INTO p_aufnr UP TO 1 ROWS
    WHERE kdauf EQ p_vbeln .
B *******
  SELECT kdauf from aufk into p_aufnr UP TO 1 ROWS
    WHERE KDAUF IN ( SELECT VBELN FROM VBAP where vbeln EQ p_vbeln) .
  ENDSELECT.
  p_rtcod = sy-subrc.
ENDFORM.                    " sales
T

Answer 1

Hi Eslam,
In select statements, ENDSELECT must be added when single line returned without the addition 'SINGLE'.
The innner query in your code, returns a single record but with the addition 'UP TO 1 ROWS'. The outer query also like this only. But the outer query ended with 'ENDSELECT', not for inner query.
Else you can add 'SINGLE' keyword.
  SELECT aufnr FROM aufk INTO p_aufnr UP TO 1 ROWS
    WHERE kdauf EQ '10' .
    SELECT SINGLE kdauf from aufk into p_aufnr
    WHERE KDAUF IN ( SELECT VBELN FROM VBAP where vbeln EQ p_vbeln) .
  ENDSELECT.
  SELECT aufnr FROM aufk INTO p_aufnr UP TO 1 ROWS
    WHERE kdauf EQ '10' .
***** It assigns Nth record's KDAUF to p_aufnr provided N records satisfy the condition.
    SELECT  kdauf from aufk into p_aufnr UPTO 1 ROWS
    WHERE KDAUF IN ( SELECT VBELN FROM VBAP where vbeln EQ 'p_vbeln) .
    ENDSELECT.
  ENDSELECT.
Regards,
R.Nagarajan.