我正在学习如何使用 SELECT CASE 但我不太明白,这里是代码:
SET @vgls=1;
SET @lgls=1;
SET @st=SELECT CASE
WHEN @vgls=@lgls THEN "emp"
WHEN @vgls>@lgls THEN "loc"
WHEN @vgls<@lgls THEN "vis" END;
SELECT @st;
它给了我以下错误:
[Err] 1064 - You have an error in your SQL syntax; check the manual that corresponds to you MySQL server version for the right syntax to use near 'SELECT CASE
WHEN @vgls=@lgls THEN "emp"
WHEN @vgls>@lgls THEN "loc"
WHEN @vg' at line 1
你需要使用SELECT ... INTO
SELECT
...
INTO var_name [, var_name]]
代替set
将 SELECT 的结果分配给变量。所以应该这样做:
SELECT CASE
WHEN @vgls=@lgls THEN "emp"
WHEN @vgls>@lgls THEN "loc"
WHEN @vgls<@lgls THEN "vis" END
INTO @st;
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