Tsql 如何使用T-SQL和XQuery选择多行作为单个XML列

给定以下数据集，我希望数据按

Name

分组，但

RoleID

、

RoleName

、

PermissionID

和

PermissionName

的值作为单个XML值放在一起：

Name            RoleID      RoleName      PermissionID PermissionName
--------------- ----------- ------------- ------------ ---------------
User 1          2           Super User    1            View
User 1          2           Super User    2            Create
User 1          2           Super User    3            Edit
User 1          2           Super User    4            Delete
User 1          3           Report User   17           Execute

所以，我想要得到的输出应该是这样的：

 Name        Roles
------------ -------------------------------------------------------
 User 1      <Roles>
                <Role id="2" name="Super User">
                    <Permissions>
                        <Permission id="1" name="View" />
                        <Permission id="2" name="Create" />
                        <Permission id="3" name="Edit" />
                        <Permission id="4" name="Delete" />
                    </Permissions>
                </Role>
                <Role id="3" name="Report User">
                    <Permissions>
                        <Permission id="17" name="Execute" />
                    </Permissions>
                </Role>
            </Roles>

---

我将您的数据集用作CTE（foo），并通过使用嵌套选择和分组方式获得所需的结果。我使用“Name”作为用户密钥，因为示例数据中没有用户ID，但您应该能够让它用于查询

with foo as
(
select
*
from
(values
('User 1','2',' Super User','1','View')
,('User 1','2',' Super User','2','Create')
,('User 1','2',' Super User','3','Edit')
,('User 1','2',' Super User','4','Delete')
,('User 1','3',' Report User','17',' Execute')
) foo(Name,RoleID,RoleName,PermissionID,PermissionName)
)

select
    Name,
    cast((
    SELECT
        B.RoleID as '@id'
        ,B.RoleName as '@name'
        ,cast((select PermissionID as '@id',PermissionName as '@name'
        from Foo C
        where c.RoleID=b.RoleID
              and c.Name=a.Name
        for xml path('Permission')
      ) as xml) Permissions
    FROM foo B
    group by 
        B.RoleID
        ,B.RoleName
    for xml path('Role'),root('Roles')
    ) as xml) Roles
from
foo a
group by Name

我尚未测试以下查询，但它应该非常接近于在您的表上运行的某个查询：

select
    U.ID as [Name],
    cast((
    SELECT
        R.[ID] as '@id'
        , R.[Name] as '@name'
        ,cast(
        (select 
            P.[ID] as '@id'
            , P.[Name] as '@name'
        from RolePermissions RP
            LEFT JOIN Permission P ON
            RP.[PermissionID] = P.[ID]
        where R.[ID] = RP.[RoleID]
        for xml path('Permission')
      ) as xml) [Permissions]
    FROM UserRoles UR
        Left Join Role R
        ON UR.[RoleID] = R.[ID]
        where U.[ID] = UR.[UserID]
    group by 
        R.[ID]
        ,R.[Name]
    for xml path('Role'),root('Roles')
    ) as xml) [Roles]
from
User U
group by ID
WHERE
    U.[ID] = 1234

---

如果为XML路径（'Role'）、根（'Roles'）指定

，则不需要强制转换为XML，并键入“

。Reference：：通过指定type指令，请求将FOR-XML查询的结果作为XML数据类型返回。PS：您可以在上进行快速测试。更多有趣的内容，请参见我的个人资料。

select
    U.ID as [Name],
    cast((
    SELECT
        R.[ID] as '@id'
        , R.[Name] as '@name'
        ,cast(
        (select 
            P.[ID] as '@id'
            , P.[Name] as '@name'
        from RolePermissions RP
            LEFT JOIN Permission P ON
            RP.[PermissionID] = P.[ID]
        where R.[ID] = RP.[RoleID]
        for xml path('Permission')
      ) as xml) [Permissions]
    FROM UserRoles UR
        Left Join Role R
        ON UR.[RoleID] = R.[ID]
        where U.[ID] = UR.[UserID]
    group by 
        R.[ID]
        ,R.[Name]
    for xml path('Role'),root('Roles')
    ) as xml) [Roles]
from
User U
group by ID
WHERE
    U.[ID] = 1234