ERROR 1221 (HY000): Incorrect usage of UNION and ORDER BY

union和union all区别

UNION会把两个查询语句的结果集合并起来。
union会过滤掉两个结果集中重复的行，而union all不会过滤掉重复行。

union / order by

在union两个带order的select的时候，会报错。

ERROR 1221 (HY000): Incorrect usage of UNION and ORDER BY

解决方法就是使用括号，把两个SELECT括起来。

例如：

(SELECT A,B,C FROM `s` ORDER BY A DESC) 
UNION 
(SELECT A,B,C FROM `r` ORDER BY B DESC);

或用SELECT AS TABLE

SELECT * FROM 
(SELECT A,B,C FROM `s` ORDER BY A DESC)
AS t1 
UNION 
SELECT A,B,C FROM `r` ORDER BY B DESC;

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原文链接：https://blog.csdn.net/lilongsy/article/details/84969097