How can I add the extra fields to a datasource usign "User Exist"?

Question

Hallo guys,
I have a quesiton on an extractor.
I want to extend fields for an extractor, and the additional fields come from a third table (for the extractor, there is a view which 2 Tabels inner join.) The third table should have LEFT OUTER JOIN relation to the other 2 tables. So I have to use "User Exist" to add the fields from the third table to my data source.
How  can I do it via user exist?
Thanks for any hint in advance.
Regards,
Liying

Answer 1

Hi LiYing,
You can do this using a USER EXIT.
if you edit the ABAP program ZXRSAU01, you can add ABAP coding:
here an example for 1_CO_PA....:
<i>   CASE i_datasource.
       WHEN '1_CO_PA_.......
Data assignments
      LOOP AT c_t_data INTO wa_s_copa.
        IF ( NOT wa_s_copa-vrgar = 'F' ) OR ( wa_s_copa-curtype = 'B0' ).
        wa_s_copa-zzratio = 1.
        wa_s_copa-zztr_rate = 1.
        wa_s_copa-zzcurkey_tc = wa_s_copa-rec_waers.
Company Code Currency Invoice *
      ELSEIF wa_s_copa-curtype = '10'.
assume one exchange rate per invoice
        SELECT SINGLE * FROM ce19991 INTO wa_ce1
           WHERE belnr = wa_s_copa-belnr
           AND   paledger = '02'
           AND   vrgar    = wa_s_copa-vrgar
           AND   versi    = space
           AND   perio    = wa_s_copa-perio.
        MOVE wa_ce1-kursf TO lx_kursf.
        MOVE wa_ce1-frwae TO wa_s_copa-zzcurkey_tc.
        IF NOT wa_ce1-frwae EQ 'EUR'.
read rate ( table is buffered ).
          CLEAR: wa_tfact, wa_ffact.
          lx-datlo = 99999999 - sy-datlo.
          SELECT single tfact ffact FROM tcurf into
          (wa_tfact, wa_ffact)
          WHERE kurst EQ 'M'
          AND fcurr EQ wa_ce1-frwae
          AND tcurr EQ 'EUR'
          AND gdatu LE lx-datlo.
          IF sy-subrc NE 0.
            SELECT single tfact ffact FROM tcurf into
            (wa_tfact, wa_ffact)
            WHERE kurst EQ 'EURX'
            AND fcurr EQ wa_ce1-frwae
            AND tcurr EQ 'EUR'
            AND gdatu LE lx-datlo.
          ENDIF.
          IF wa_tfact = 1.
            wa_s_copa-zzratio = wa_ffact.
          ELSE.
            IF wa_tfact NE 0.
              wa_s_copa-zzratio = 1 / wa_tfact.
            ENDIF.
          ENDIF.
        ELSE.
eur : eur => always 1
          wa_s_copa-zzratio = 1.
        ENDIF.
        IF lx_kursf < 0.
          wa_s_copa-zztr_rate = lx_kursf * -1 .
        ELSE.
          CHECK lx_kursf > 0.
          wa_s_copa-zztr_rate = 1 / lx_kursf.
        ENDIF.
      ENDIF.
  ENDLOOP.
ENDCASE.
</i>