Question

我正在努力解决（最有可能）非常简单的问题。我一直收到以下错误：

Error: ambiguous column name: Rek.name

好的，我理论上知道这个错误意味着什么。但是，当我尝试使用它时，我不明白它出现的原因：

SELECT DISTINCT Rek.name AS abc, COUNT(DISTINCT Fav.FavId) AS def
FROM Rek, Fav
LEFT JOIN Artist ON Rek.RekId = Fav.RekId;

为什么Rek.name含糊不清？怎么能让它变得不模糊？

Answer 1

如果你想加入Fav表：

SELECT DISTINCT Rek.name AS abc, COUNT(DISTINCT Fav.FavId) AS def
FROM Rek
LEFT JOIN Fav ON Rek.RekId = Fav.RekId
GROUP BY Rek.name;

如果你还想要艺术家表：

SELECT DISTINCT Rek.name AS abc, COUNT(DISTINCT Fav.FavId) AS def
FROM Rek
LEFT JOIN Fav ON Rek.RekId = Fav.RekId
LEFT JOIN Artist ON Rek.common_attribute= Artist.common_attribute
GROUP BY Rek.name;

Answer 2

咦？我认为你想要的查询是这样的：

SELECT Rek.name AS abc, COUNT(Fav.RekId) AS def
FROM Rek LEFT JOIN
     Fav
     ON Rek.RekId = Fav.RekId
GROUP BY Rek.name;

注意：

不需要Artist表。
SELECT DISTINCT是一种执行GROUP BY的尴尬方式。
据推测，fav.favid是主键。在这种情况下，您不需要COUNT(DISTINCT)。

左连接＆amp;模棱两可的错误

2 个答案: