組由結果通過SUM我有3個表:MySQL的 - 2列
user(id, name, id_school)
school(id, name)
result(id_user, stage1, stage2)
現在我想獲得學校的排名 - 是2列的總和:stage1和stage2所有用戶。
組由結果通過SUM我有3個表:MySQL的 - 2列
user(id, name, id_school)
school(id, name)
result(id_user, stage1, stage2)
現在我想獲得學校的排名 - 是2列的總和:stage1和stage2所有用戶。
試試這個查詢。它只是assumption.please提供一些數據進行測試
SELECT
s.id,
s.name AS SchoolName
(r.S1 + r.S2) AS Rank
FROM school as s
LEFT JOIN user as u ON u.id_school = s.id
LEFT JOIN (SELECT id_user , SUM(stage1) as S1 , SUM(stage2) FROM result GROUP BY id_user) as r ON r.id_user = u.id
GROUP BY s.id
ORDER BY Rank DESC
我會做這樣的事情:
SELECT school.name, SUM(result.result1 + result.result2)
FROM school LEFT JOIN user ON (user.id_school = school.id) LEFT JOIN result ON (result.id_user = user.id) GROUP BY school.id
希望它能幫助,祝你好運:)
顯得過於簡單:
select s.name as school, sum(stage1)+sum(stage2) as rank
from result r
join user u on u.id=r.id_user
join school s on s.id=u.id_school
group by s.id
我真的希望你有索引。
isnt s.name應該在groupby子句中嗎? – DevelopmentIsMyPassion 2013-02-15 13:14:30
@AshReva不在mysql中,在這裏稱之爲「優化」) – 2013-02-15 13:16:08
看來我確實錯過了:( – DevelopmentIsMyPassion 2013-02-15 13:16:26
請顯示您已經嘗試過的陳述。 – 2013-02-15 12:53:35