mysql计算group_concat中的项目

Question

我在 MySQL 中使用 GROUP_CONCAT 时遇到问题 我的表格

g0

如下：

ID  Age Sex
-------------
1   16  Male
2   18  Female
3   16  Male
4   18  Female
5   16  Male

但是我需要桌子看起来像这样

ID        count
1,3,5       3
2,4         2

我尝试了这个查询：

SELECT GROUP_CONCAT(
CONCAT(cnt)) cnts FROM 
(SELECT COUNT(ID) as cnt FROM g0  GROUP BY Age , Sex order by ID Desc) ;

但是我收到此错误消息：

1248. Every derived table must have it's own alias

Answer 1

无需在

count

内包含

group_concat

- 只需将其选择为具有相同

group by

表达式的不同项目即可：

SELECT   GROUP_CONCAT(id), COUNT(*)
FROM     g0
GROUP BY age, sex
ORDER BY 1 DESC

Answer 2

选择 GROUP_CONCAT( CONCAT（cnt））cnts FROM (SELECT COUNT(ID) as cnt FROM g0 GROUP BY Age , Sex order by ID Desc) AS cnts;