How to construct Dynamic Join in ABAP?

Question

Hello ALL,
I am typically faced with a situvation where in I need to write a dynamic JOIN SQL statement in ABAP.
For example :
REPORT ZTEST .
PARAMETERS: TBLNAME(50) DEFAULT 'SPFLI'.
DATA: TOTAL_ROWS TYPE P.
SELECT COUNT(*) FROM (TBLNAME) INTO TOTAL_ROWS.
WRITE: / TBLNAME, TOTAL_ROWS.
In the above example, here the fetch from Table is dynamic.
Where as if i have to conisder the following SQL statement which is a normal JOIN statement in ABAP,
select
  mara~matnr
  marc~werks
  from mara
  join marc on maramatnr = marcmatnr
  into table it_join
  where mara~mtart = 'FERT' and
        marc~werks = '3000'.
How do i convert this into DYNAMIC JOIN STATEMENT</b> .
Looking forward to your responses.
Thank you

Answer 1

Hi,
This is from the ABAP keyword help in 6.40, not sure if it works in previous releases or not.
Example
Dynamic specification of the inner joins. The column specification after SELECT is also dynamic.
PARAMETERS: p_cityfr TYPE spfli-cityfrom,
            p_cityto TYPE spfli-cityto.
DATA: BEGIN OF wa,
         fldate TYPE sflight-fldate,
         carrname TYPE scarr-carrname,
         connid   TYPE spfli-connid,
       END OF wa.
DATA itab LIKE SORTED TABLE OF wa
               WITH UNIQUE KEY fldate carrname connid.
DATA: column_syntax TYPE string,
      dbtab_syntax TYPE string.
column_syntax = `ccarrname pconnid f~fldate`.
dbtab_syntax = `( ( scarr AS c `
  & ` INNER JOIN spfli AS p ON pcarrid  = ccarrid`
  & ` AND p~cityfrom = p_cityfr`
  & ` AND p~cityto   = p_cityto )`
  & ` INNER JOIN sflight AS f ON fcarrid = pcarrid `
  & ` AND fconnid = pconnid )`.
SELECT (column_syntax)
       FROM (dbtab_syntax)
       INTO CORRESPONDING FIELDS OF TABLE itab.
LOOP AT itab INTO wa.
  WRITE: / wa-fldate, wa-carrname, wa-connid.
ENDLOOP.
Regards
Vilmos