Question

我有3个表-Users，Images和Users_Images。每个用户可以购买许多图像，并且每个图像可以由多个用户购买。表中的字段如下：

Users - Id, UserName, Password

Images - Id, Name, Description, Path

Users_Images - UserId, ImageId, PurchaseDate。（表之间的所有关系都已设置）我正在尝试建立一个查询，该查询将选择一个表，其中包含特定用户尚未购买的所有图像我的算法是选择一张包含所有已购买特定用户的图像的表，然后从整个图像表中减去该表。但是，无论我如何尝试将其写为查询，它总是给我错误或不完整的结果。我尝试过的一些查询：

SELECT Id, [Name], Description, Path 
FROM Images
EXCEPT
SELECT Id, [Name], Description, Path 
FROM Images AS I INNER JOIN Users_Images AS UI
ON I.Id = UI.ImageId
WHERE UserId = 1

OR

SELECT Id, [Name], Description, Path 
FROM Images
WHERE NOT EXISTS (
SELECT Id, [Name], Description, Path 
FROM Images AS I INNER JOIN Users_Images AS UI
ON I.Id = UI.ImageId
WHERE UserId = 1)

我也在这里和其他网站上搜索解决方案，但是没有一个起作用。

Answer 1

使用not in

select im.Name,im.Description,im.Path from Images im where im.id not in (

select i.id Users_Images ui join Images i on ui.ImageId=i.id
join Users u on ui.UserId=u.Id
where u.UserId=1
)

Answer 2

您的第二个版本需要关联：

SELECT im.*
FROM Images im
WHERE NOT EXISTS (SELECT 1
                  FROM Images AS I INNER JOIN 
                       Users_Images AS UI
                       ON I.Id = UI.ImageId
                  WHERE UI.UserId = 1 AND I.Id = im.Id
                 );

Answer 3

这对您有用吗？

SELECT Id, [Name], Description, Path 
FROM Images as I
WHERE NOT EXISTS (SELECT 1
                  FROM Users_Images AS UI
                  WHERE UI.ImageId = I.Id AND
                        UI.UserId = 1
                 );

这只是返回用户ID为1的user_images中没有行的所有图像。

从Access中的另一个表中减去表

3 个答案: