在 ABAP 中使用一个或多个 IF 语句的 SELECT 查询

Question

我正在开发一项网络服务。我有一个这样的 select 语句（它比这有更多的字段和 2 个连接，但为了保持简单）：

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.

我需要添加这个 IF 语句：

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.

我需要一个不会影响服务性能的答案。因为 ACDOCA 和 BSEG 是 SAP 中一些最大的数据库表。我尝试在 SELECT 之后使用 LOOP，然后在该 LOOP 中添加这个 IF，但这完全破坏了性能。

This Is What IT_ACDOCA table should look like after

希望快速回复。 最好的问候。

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 EQ 'D' OR bseg~koart EQ 'K' ) AND 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.

如果您的版本不支持 CASE，您可以将您的语句添加到 JOIN 端，如下所示。

SELECT acdoca~augbl,
       dmbtr 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
                      AND ( bseg~koart EQ 'D' OR bseg~koart EQ 'K' )
                      AND acdoca~AUGBL is INITIAL
INTO TABLE @it_acdoca.