使用 ABAP 中的一个或多个 IF 语句进行 SELECT 查询

Question

I'm working on a web service. I have a select statement like this (it has much more fields and 2 more joins than this but to keep it simple):

SELECT acdoca~augbl,
       open_amount,    "I need to add value to this field based on the IF statement below
       acdoca~koart
FROM acdoca
      LEFT JOIN bseg ON acdoca~belnr EQ bseg~belnr
                      AND acdoca~gjahr EQ bseg~gjahr
                      AND acdoca~buzei EQ bseg~buzei
                      AND acdoca~rbukrs EQ bseg~bukrs
INTO table @it_acdoca.

I need to add this IF statement:

IF bseg-KOART = 'D' or bseg-KOART = 'K' 
    IF acdoca-AUGBL is INITIAL THEN open_amount = DMBTR
        ELSE open_amount = 0
    ENDIF.
ELSE open_amount = 0
ENDIF.

I need an answer that won't trash the performance of the service. Since ACDOCA and BSEG are some of the biggest database tables in SAP. I tried using LOOP after SELECT and then adding this IF inside that LOOP but that destroyed the performance totally.

This Is What IT_ACDOCA table should look like after

Hoping for a quick reply. Best regards.

Answer 1

DATA: BEGIN OF it_acdoca  OCCURS 0,
        augbl       TYPE acdoca-augbl,
        open_amount TYPE bseg-dmbtr,
        koart       TYPE acdoca-koart.
DATA: END OF it_acdoca.

SELECT acdoca~augbl,
       CASE WHEN bseg~koart NE 'D' AND bseg~koart NE 'K' THEN 0
            WHEN acdoca~augbl IS INITIAL THEN dmbtr
            ELSE 0
       END AS open_amount,
       acdoca~koart
FROM acdoca
      LEFT JOIN bseg ON acdoca~belnr EQ bseg~belnr
                      AND acdoca~gjahr EQ bseg~gjahr
                      AND acdoca~buzei EQ bseg~buzei
                      AND acdoca~rbukrs EQ bseg~bukrs
INTO TABLE @it_acdoca.

If your version not supported CASE you can prepare different queries for statement and merge responses. Also you can run these queries in parallel.