mysql - 将 ORDER BY 应用于 UNION MYSQL

Question

我尝试在 UNION 组合中使用 ORDER BY 表达式，但收到错误

"Expression #1 of ORDER BY contains aggregate function and applies to a 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 上设置一个工作示例.

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，您可以使用一个更简单的解决方案，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 中看到它的作用