1、有三张表，用户表，用户角色表，角色表，
使用sql显示如下内容：
用户ID，用户名，超级管理员，录入员，会计
也就是角色用逗号分隔。
解：

1、填充数据到表User
select * from [User]
INSERT INTO [northwind].[dbo].[User]
           ([ID]
           ,[NAME])
     VALUES
           (1
           ,'zhaohy')
           INSERT INTO [northwind].[dbo].[User]
           ([ID]
           ,[NAME])
     VALUES
           (2
           ,'zhangyy')
GO

2、填充数据到表role
select * from [role]
INSERT INTO [northwind].[dbo].[Role]
           ([ID]
           ,[RoleName])
     VALUES
           (1
           ,'senior software engineer')
           INSERT INTO [northwind].[dbo].[Role]
           ([ID]
           ,[RoleName])
     VALUES
           (2
           ,'project manager')
                    INSERT INTO [northwind].[dbo].[Role]
           ([ID]
           ,[RoleName])
     VALUES
           (3
           ,'UI Disigner')
                               INSERT INTO [northwind].[dbo].[Role]
           ([ID]
           ,[RoleName])
     VALUES
           (4
           ,'Tester')
GO
3、填充数据到表Role_User
select * from Role_User
INSERT INTO [northwind].[dbo].[Role_User]
           ([RoleID]
           ,[UserID])
     VALUES
           (1
           ,1)
GO
INSERT INTO [northwind].[dbo].[Role_User]
           ([RoleID]
           ,[UserID])
     VALUES
           (2
           ,1)
           INSERT INTO [northwind].[dbo].[Role_User]
           ([RoleID]
           ,[UserID])
     VALUES
           (3
           ,1)
                      INSERT INTO [northwind].[dbo].[Role_User]
           ([RoleID]
           ,[UserID])
     VALUES
           (4
           ,2)

4、查询出来：
drop table #result;
select * into #result from (select u.ID,u.NAME,ru.RoleID,r.RoleName from [user] u inner join Role_User ru on ru.UserID =u.ID inner join [Role] r
on ru.RoleID=r.ID) as t;
select * from #result;
select id,name, [RoleName] = stuff((select ',' + [RoleName] from #result t where id = #result.id for xml path('')) , 1 , 1 , '') 
from #result 
group by id ,name;
drop table #result;
输出结果：