MySQL连接，其中forgein Key=id1和forgein Key=id2

这个问题让我的大脑有点迟钝，我发现很难找到解决办法，因为我不能正确地表达这个问题来提供相关信息

我正试图从下表中获取fProduct记录，其中有一个fAttribute 2号和20号

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

当我希望返回FPProduct的2295和3008时，我下面的陈述产生了0个结果

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

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有人能帮忙吗？

您可以使用内部联接，也可以使用现有条件：

内部联接：

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)

---

可以使用内部联接，也可以使用现有条件：

内部联接：

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)

加入应有助于：

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

加入应有助于：

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

---

由于您已经通过将WHERE子句更改为OR或IN并添加HAVING COUNTfattribute=2来进行分组，从而确保它同时具有这两个属性

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

---

由于您已经通过将WHERE子句更改为OR或IN并添加HAVING COUNTfattribute=2来进行分组，从而确保它同时具有这两个属性

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

---

在where子句之前和中，You's missing=2在where子句之前和中，You's missing=2在where子句中，我最后使用了内部联接选项。干杯，老兄。@Theokouzeli很高兴我能帮上忙！！我最后使用了内部连接选项。干杯，老兄。@Theokouzeli很高兴我能帮上忙！！