SQL从解码切换到大小写 [英] SQL switch from decode to case

问题描述

我有一个查询，它执行的操作是这样的...

I have a query that does something like this...

SELECT * FROM ...
...
ORDER BY DECODE(APR(ACC.RATE,'X'), 'FIRST RATE', 1, 'SECOND RATE', 2, 3);

因为我正在处理h2数据库，并且h2没有解码，并且解码别名很难实现，所以我想知道是否可以将此DECODE转换为CASE语句.如何转换?

Because I am dealing with h2 database and h2 doesnt have decode and decode alias is very difficult to implement so I was wondering if I could convert this DECODE into CASE statement. How do I convert it?

推荐答案

解码意味着:

CASE FirstParam
  WHEN SecondParam THEN ThirdParam 
  WHEN FourthParam THEN FifthParam
  WHEN SixthParam THEN Seventh... etcetera
  ELSE LastParam -- If number of params is odd, otherwise ELSE NULL is implied
END

所以

CASE APR(ACC.RATE,'X')
  WHEN 'FIRST RATE' THEN 1
  WHEN 'SECOND RATE' THEN 2
  ELSE 3
END

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