MySQL JOIN WHERE forgein Key = id1 AND forgein Key = id2

Question

我对这个问题有一点脑块，我发现很难搜索解决方案，因为我不能正确地提出问题来调出相关问题信息。

我试图从表中取回“fProduct”记录下面的地方有一个“fAttribute”的2 和20

id fAttribute fProduct 
19  2  2967 
48  2  2923 
50  2  3008 
51  20  3008 
52  2  2295 
53  20  2295 

下面我statment产生0结果时，我会希望返回fProduct的2295和3008.

SELECT fProduct 
FROM tableName 
WHERE fAttribute = 2 AND fAttribute = 20 
GROUP BY fProduct 

任何人都可以帮忙吗？

Answer 1

您可以使用内部连接或使用EXISTS条件：

INNER JOIN：

SELECT DISTINCT a.fProduct 
FROM MyTable a 
    INNER JOIN MyTable b ON a.fProduct = b.fProduct AND b.fAttribute = 2 
    INNER JOIN MyTable c ON a.fProduct = c.fProduct AND c.fAttribute = 20 

存在：

SELECT afproduct 
FROM MyTable a 
WHERE EXISTS (SELECT b.id FROM MyTable b WHERE a.fProduct = b.fProduct AND b.fAttribute = 2) 
    AND EXISTS (SELECT c.id FROM MyTable c WHERE a.fProduct = c.fProduct AND c.fAttribute = 20) 

Answer 2

联接应该有所帮助：

SELECT distinct a.fProduct 
FROM tableName as a 
join tableName as b on b.product = a.product 
WHERE a.fAttribute = 2 and b.fAttribute = 20 

Answer 3

既然你是已经在做GROUP BY只是将您的WHERE子句更改为OR或IN并添加HAVING COUNT(fattribute) = 2，以确保它们都具有。

SELECT fproduct 
FROM tablename 
WHERE fattribute IN (2 , 20) 
GROUP BY fproduct 
HAVING COUNT(fattribute) = 2