Oracle SQL - SCD 跟踪随时间变化的属性

Question

我遇到了以下错误：

ORA-30483: window  functions are not allowed here
30483. 00000 -  "window  functions are not allowed here"

我正在尝试构建 BOOK_NO 和 WALK_NO 属性随时间变化的水平视图。

我认为一个合理的方法是对 effective_to 日期进行排名，然后只解码该值的 book_no||walk_no 属性....但不确定去哪里从这里开始！

SQL 下面:

Select METER_PIT_REF 
,MAX(DECODE( RANK() OVER (PARTITION BY METER_PIT_REF ORDER BY EFFECTIVE_TO DESC),1,BOOK_NO||WALK_NO) )
,MAX(DECODE( RANK() OVER (PARTITION BY METER_PIT_REF ORDER BY EFFECTIVE_TO DESC),2,BOOK_NO||WALK_NO) )
,MAX DECODE( RANK() OVER (PARTITION BY METER_PIT_REF ORDER BY EFFECTIVE_TO DESC),3,BOOK_NO||WALK_NO) )
FROM BW_PIT_BOOKWALK_BRIDGE
WHERE BOOK_NO = 'M04'
GROUP BY METER_PIT_REF

非常感谢任何建议！

Answer 1

使用子查询：

Select METER_PIT_REF,
       MAX(CASE WHEN r = 1 THEN BOOK_NO||WALK_NO END),
       MAX(CASE WHEN r = 2 THEN BOOK_NO||WALK_NO END),
       MAX(CASE WHEN r = 3 THEN BOOK_NO||WALK_NO END)
FROM (SELECT b.*,
             RANK() OVER (PARTITION BY METER_PIT_REF ORDER BY EFFECTIVE_TO DESC) as r
      FROM BW_PIT_BOOKWALK_BRIDGE
     ) b
WHERE BOOK_NO = 'M04'
GROUP BY METER_PIT_REF;

我也用 CASE 替换了 DECODE()。它是等效的 ANSI 标准。

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