我有以下数据库(小例子):
ID | username | action | points
1 | matt | login | 3
2 | john | comment | 6
3 | john | login | 6
4 | peter | login | 8
5 | peter | login | 8
而且我不确定如何选择和分组具有相同操作(=登录)和高于5的用户名(对于所有操作).
预期成绩:
username | COUNT | points(SUM)
peter | 2 | 16
我尝试了子查询,但找不到合适的解决方案.你知道怎么做吗?非常感谢您的帮助!
对不起,我没有强调这一事实,即所有操作都必须登录.因此,结果将没有john,因为有与此用户名相关的操作注释.
最佳答案
SELECT username, COUNT(*) AS cnt, SUM(points) AS points
FROM tableX AS t
GROUP BY username
HAVING COUNT(*) = COUNT(CASE WHEN action = 'login' THEN action END)
AND SUM(points) > 5 ;
要么:
SELECT username, COUNT(*) AS cnt, SUM(points) AS points
FROM tableX AS t
WHERE action = 'login'
AND NOT EXISTS
( SELECT *
FROM tableX AS tt
WHERE tt.username = t.username
AND ( tt.action <> 'login' OR tt.action IS NULL )
)
GROUP BY username
HAVING SUM(points) > 5 ;
但我认为,通过索引(用户名,登录名)和一个(用户名,点数),这将是最有效的:
SELECT username, COUNT(*) AS cnt, SUM(points) AS points
FROM tableX AS t
GROUP BY username
HAVING MIN(action) = 'login'
AND MAX(action) = 'login'
AND SUM(points) > 5 ;