比賽各變量在MySQL（通過）

Question

基本上我有以下查詢：

SELECT DISTINCT users.ID, users.name 
FROM users 
INNER JOIN usersSkills ON users.ID = usersSkills.userID 
INNER JOIN usersLanguages ON users.ID = usersLanguages.userID 
WHERE activated = "1" 
AND type = "GRADUATE" 
AND usersSkills.skillID IN(2, 21) 
AND usersLanguages.languageID IN(2, 22) 

我需要的skillID和languageID匹配的那一刻每個在IN（）函數傳遞每個參數如果找到任何參數，那麼它將提供結果。

所以基本上我只希望看到的結果，如果2個和21個技能ID是在技能表和語言同樣的想法找到...

Answer 1

使用GROUP BY（這也將消除需要SELECT DISTINCT）來獲取聚合計數和HAVING子句，以確保返回的不同元素的計數與您正在搜索的元素的數量相匹配。

SELECT users.ID, users.name 
FROM users 
INNER JOIN usersSkills ON users.ID = usersSkills.userID 
INNER JOIN usersLanguages ON users.ID = usersLanguages.userID 
WHERE activated = "1" 
AND type = "GRADUATE" 
AND usersSkills.skillID IN(2, 21) 
AND usersLanguages.languageID IN(2, 22) 
GROUP BY users.ID, users.name 
HAVING COUNT(DISTINCT usersSkills.skillID) = 2 
    AND COUNT(DISTINCT usersLanguages.languageID) = 2