查询分隔列值

Question

我想知道这是为什么代码不会返回任何结果

SELECT A.PermissionGroupID, A.ApplicationID, CONVERT(nvarchar(5),A.PermissionID) AS Permission, A.PermissionName, B.PermissionGroupName, C.ApplicationName 
    FROM Permission AS A 
    JOIN PermissionGroup AS B ON A.PermissionGroupID = B.PermissionGroupID 
LEFT JOIN Application AS C ON A.ApplicationID = C.ApplicationID 
    WHERE (A.Active = 1) 
     AND (CONVERT(nvarchar(2),A.PermissionID) IN (SELECT Permissions 
                FROM UserPermissions 
                WHERE UserID = 1)) 

但是这一次是工作

SELECT A.PermissionGroupID, A.ApplicationID, CONVERT(nvarchar(5),A.PermissionID) AS Permission, A.PermissionName, B.PermissionGroupName, C.ApplicationName 
    FROM Permission AS A 
    JOIN PermissionGroup AS B ON A.PermissionGroupID = B.PermissionGroupID 
LEFT JOIN Application AS C ON A.ApplicationID = C.ApplicationID 
    WHERE (A.Active = 1) 
     AND (CONVERT(nvarchar(2), A.PermissionID) IN ('5','6','7','8')) 

这里是我的权限表的内容

Permission 
-------------------------------- 
Permission Permission Application Permission 
ID   Group   ID    Name 
4   1    1   VISA_APPLICATION_DELETE 
5   1    1   VISA_APPLICATION_PRINT 
6   4    10   APPLICATION_ADD 
7   4    10   APPLICATION_EDIT 
8   4    10   APPLICATION_DELETE 
9   4    10   APPLICATION_VIEW 

这里是我的UserPermissions表

的内容

UserPermissions 
-------------------------- 
UserPermission  UserID Permissions 
ID 
2   1   5,6,7,8 -> I tried to change it manually to this format ('5','6','7','8') but to no avail. 

Answer 1

为什么我怀疑权限看起来像一个字符串“5,6,7,8”。我期望查询是“PermisionId（选择PermissionId from ...）”，而不是（选择权限）。

假设是这种情况，查询以下版本应该解决您的问题：

SELECT A.PermissionGroupID, A.ApplicationID, CONVERT(nvarchar(5),A.PermissionID) AS Permission, 
     A.PermissionName, B.PermissionGroupName, C.ApplicationName 
FROM Permission A JOIN 
    PermissionGroup B 
    ON A.PermissionGroupID = B.PermissionGroupID LEFT JOIN 
    Application AS C 
    ON A.ApplicationID = C.ApplicationID cross JOIN 
    (SELECT Permissions 
     FROM UserPermissions 
     WHERE UserID = 1 
    ) p1 
WHERE (A.Active = 1) AND 
     charindex(','+CONVERT(nvarchar(2)+',', A.PermissionID)+',', ','+p1.Permissions+',') > 0 

注意我前插和追加逗号因此“1”不匹配“15”。另外，这假定每个用户的UserPermissions中只有一行。

顺便说一下，您应该修复您的模式，以便UserPermissions为每个用户和权限分别设置一行，这样您的原始公式就可以工作。

Answer 2

从评论我看到你担心表现。性能问题是由于您存储逗号分隔的值的字符串，因此每个值应该有一行。
将表UserPermissions更改为这样的内容。

create table UserPermissions 
(
    UserID int references Users(UserID), 
    PermissionID int references Permission(PremissionID), 
    primary key (UserID, PermissionID) 
) 

和您的查询应该是...

SELECT A.PermissionGroupID, 
     A.ApplicationID, 
     A.PermissionID, 
     A.PermissionName, 
     B.PermissionGroupName, 
     C.ApplicationName 
FROM Permission AS A 
    JOIN PermissionGroup AS B 
    ON A.PermissionGroupID = B.PermissionGroupID 
    LEFT JOIN Application AS C 
    ON A.ApplicationID = C.ApplicationID 
WHERE A.Active = 1 AND 
     A.PermissionID IN (SELECT PermissionID 
         FROM UserPermissions 
         WHERE UserID = 1)