CASE语句中的WHERE子句

Question

Can i use WHERE clause inside a CASE statement as given below?

CASE WHEN A=1 THEN B WHERE C=0 ELSE A END

Answer 1

你可以简单地写

CASE WHEN A=1 AND C=0 THEN B ELSE A END;

Answer 2

在你的情况下试试这个

CASE WHEN (A=1 AND C=0) THEN B ELSE A END AS Field_Name

Answer 3

不，只是使用

CASE WHEN A=1 AND C=0 THEN B ELSE A END

Answer 4

您也可以这样操作：

CASE WHEN A=1 THEN B WHEN B=1 THEN A ELSE C END

Answer 5

CASE A 
WHEN 1 THEN A 
WHEN 2 THEN B 
ELSE C END

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