将 ORDER BY 应用于 UNION MYSQL

Question

我正在尝试在UNION 的组合中使用ORDER BY 表达式，但收到错误消息

“ORDER BY 的表达式 #1 包含聚合函数并适用于 UNION”。

(SELECT 'SELECT' AS argument, count(argument) FROM mysql.general_log WHERE 
argument LIKE ("SELECT%"))
UNION
(SELECT 'INSERT' AS argument, count(argument) FROM mysql.general_log WHERE 
argument LIKE ("INSERT%"))
UNION
(SELECT 'UPDATE' AS argument, count(argument) FROM mysql.general_log WHERE 
argument LIKE ("UPDATE%"))
UNION
(SELECT 'DELETE' AS argument, count(argument) FROM mysql.general_log WHERE 
argument LIKE ("DELETE%"))
ORDER BY count(argument) ASC;

Answer 1

正确的语法是

select * from
( query 1 union query 2 union query 3...)
order by x

编辑

您还缺少计数和外部查询的别名。最终查询应如下所示

这足以让我在 rextester 上建立一个工作示例。

SELECT argument, cnt from
(
    (SELECT 'SELECT' AS argument, count(argument) as CNT FROM mysql.general_log WHERE 
    argument LIKE ("SELECT%"))
    UNION
    (SELECT 'INSERT' AS argument, count(argument) FROM mysql.general_log WHERE 
    argument LIKE ("INSERT%"))
    UNION
    (SELECT 'UPDATE' AS argument, count(argument) FROM mysql.general_log WHERE 
    argument LIKE ("UPDATE%"))
    UNION
    (SELECT 'DELETE' AS argument, count(argument) FROM mysql.general_log WHERE 
    argument LIKE ("DELETE%"))
) aa
ORDER BY cnt ASC;

不过有一个更简单的解决方案，您可以使用它，因为参数的长度都相同：

select  substring(upper(argument), 1, 6) as argument, count(*) as cnt
from    mysql.general_log
group by substring(upper(argument), 1, 6)
order by cnt asc;

您可以在我上面链接的同一个 rextester 中看到这一点