SQL查询将具有相同索引的多个项分组到同一行中

因此，我有三个表，其中包含关于用户及其部门的数据，我需要创建一个查询来组织他们之间的数据。第一个表包含用户名及其ID，如下所示：

user_name   user_id
-----------------------
bob         1
chuck       2
bill        3

user_id     department_id
-----------------------------
1           x
1           y
2           x
3           z
2           z
2           y

user_name   user_id     department_1    department_2    department_3
----------------------------------------------------------------------------
bob         1           research        development
chuck       2           research        development     advertising
bill        3           advertising

user_name   user_id     department_1    department_2    department_3
----------------------------------------------------------------------------
bob         1           research        research        research
bob         1           development     development     development
chuck       2           research        research        research
chuck       2           development     development     development
chuck       3           advertising     advertising     advertising
bill        3           advertising     advertising     advertising

下一个表使用用户的部门ID对用户进行索引，如下所示：

user_name   user_id
-----------------------
bob         1
chuck       2
bill        3

user_id     department_id
-----------------------------
1           x
1           y
2           x
3           z
2           z
2           y

user_name   user_id     department_1    department_2    department_3
----------------------------------------------------------------------------
bob         1           research        development
chuck       2           research        development     advertising
bill        3           advertising

user_name   user_id     department_1    department_2    department_3
----------------------------------------------------------------------------
bob         1           research        research        research
bob         1           development     development     development
chuck       2           research        research        research
chuck       2           development     development     development
chuck       3           advertising     advertising     advertising
bill        3           advertising     advertising     advertising

最后一个表根据部门ID列出了部门名称：

department_id   department_name
-------------------------------
x               research
y               development
z               advertising

如何编写一个列出所有用户及其所在部门的查询？它应该是这样的：

user_name   user_id
-----------------------
bob         1
chuck       2
bill        3

user_id     department_id
-----------------------------
1           x
1           y
2           x
3           z
2           z
2           y

user_name   user_id     department_1    department_2    department_3
----------------------------------------------------------------------------
bob         1           research        development
chuck       2           research        development     advertising
bill        3           advertising

user_name   user_id     department_1    department_2    department_3
----------------------------------------------------------------------------
bob         1           research        research        research
bob         1           development     development     development
chuck       2           research        research        research
chuck       2           development     development     development
chuck       3           advertising     advertising     advertising
bill        3           advertising     advertising     advertising

我尝试过许多不同的方法，但我找不到任何能给我这个结果的方法。“我的输出”当前列出了具有多个部门的重复用户，如下所示：

user_name   user_id
-----------------------
bob         1
chuck       2
bill        3

user_id     department_id
-----------------------------
1           x
1           y
2           x
3           z
2           z
2           y

user_name   user_id     department_1    department_2    department_3
----------------------------------------------------------------------------
bob         1           research        development
chuck       2           research        development     advertising
bill        3           advertising

user_name   user_id     department_1    department_2    department_3
----------------------------------------------------------------------------
bob         1           research        research        research
bob         1           development     development     development
chuck       2           research        research        research
chuck       2           development     development     development
chuck       3           advertising     advertising     advertising
bill        3           advertising     advertising     advertising

当前代码：

WITH DATA AS
(
SELECT 
Users.user_name AS Name,
Users.user_id AS Id,
Departments.department_name AS Department1,
Departments.department_name AS Department2,
Departments.department_name AS Department3
FROM Users
    JOIN Department_Index ON Users.user_id = Department_Index.user_id
    JOIN Departments ON Departments.department_id = Department_Index.department_id
WHERE Departments.department_id = Department_Index.department_id
)

SELECT
Name,Id,Department1,Department2,Department3
FROM DATA

我也试过这样的东西

WITH DATA AS
(
SELECT 
Users.user_name AS Name,
Users.user_id AS Id,
( SELECT Departments.department_name
  FROM Departments
     JOIN Department_Index ON Department_Index.user_id = Users.user_id
  WHERE Departments.department_name = Department_Index.department_name
) AS Departments
FROM Users
)

SELECT
Name,Id,Departments[0],Departments[1],Departments[2]
FROM DATA

但这也不起作用

---

感谢您的帮助

在你告诉我们表名之前，我写了这个

关键是使用row_number（）窗口函数对部门名称进行排序，然后再次加入此CTE 3次

with ud_numbered as
(
   select u.user_id, ud.department_id, d.department_name
       row_number() over (partition by u.user_id order by ud.department_id asc) as dept_no
   from user_table u
   left join user_departement ud on u.user_id = ud1.user_id
   left join department d on ud.department_id = d.department_id
)
select u.user_id, u.user_name, n1.department_name as department_1,
                               n2.department_name as department_2, 
                               n3.department_name as department_3
from user_table u
left join ud_numbered n1 on u.user_id = n1.user_id and n1.dept_no = 1
left join ud_numbered n2 on u.user_id = n2.user_id and n2.dept_no = 2
left join ud_numbered n3 on u.user_id = n3.user_id and n3.dept_no = 3

---

我个人会用和来处理这个问题

ROW_NUMBER（）

将为每个部门每人提供一个唯一的标识符，从1开始，然后您可以使用此标识符来关注。所使用的聚合函数（在本例中为

MAX

）是任意的，因为如上所述，标识符无论如何都是唯一的，因此您将取单个值的

MAX

：

WITH UserData AS
(   SELECT  u.[user_id], 
            u.[user_name],
            d.department_name,
            RowNumber = ROW_NUMBER() OVER(PARTITION BY u.[user_id] ORDER BY d.department_id)
    FROM    Users AS u
            INNER JOIN Department_Index AS di
                ON di.user_id = u.user_id
            INNER JOIN Departments AS d
                ON d.department_id = di.department_id
)
SELECT  pvt.[user_id],
        pvt.[user_name],
        Department1 = pvt.[1],
        Department2 = pvt.[2],
        Department3 = pvt.[3]
FROM    Data AS d
        PIVOT 
        (   MAX(department_name)
            FOR RowNumber IN ([1], [2], [3])
        ) AS pvt;

---

你能告诉我们到目前为止你做了什么吗？你能有3个以上的部门吗？当然，如果你能知道你的表名是什么的话。。。我想我们可以猜。@威震天他们可能在3个以上的部门，但查询最多只需要返回3个。用我的代码和表名编辑了我的帖子。噢，复数名称表。按照惯例，表格将被命名为“用户”和“部门”。