查询以逗号分隔的ID为逗号分隔的值 [英] Query for comma-separated ids to comma-separated values

问题描述

我有2张桌子

部门

ID  Dept
---------
1   HR
2   Accts
3   IT

员工

ID Name     Depts
-------------------
1  Kevin     2,1
2  Michelle  1
3  Troy      1,3
4  Rheesa    2,3,1

我正在寻找带有以下SQL查询的输出.

I am looking for an output like the following with a SQL query.

员工部门

ID Name      Depts
-------------------------
 1 Kevin     Accts,HR
 2 Michelle  HR
 3 Troy      HR,IT
 4 Rheesa    Accts,IT,HR

我尝试了以下将s与dept连接起来的方法，但是仅对每个dept产生一行.如何使用查询获得以上结果?

I have tried the following that join s with depts but results in one row for each dept only. How do i get the above results using a query?

select 
    name, depts, dept 
from 
    employee
CROSS APPLY  
    dbo.split_list(employee.depts ,',') split
inner join 
    dbo.department on  depts= split.value
order by 
    name

推荐答案

DECLARE @Departments TABLE 
(
  ID INT PRIMARY KEY, 
  Dept VARCHAR(32) NOT NULL UNIQUE
);

DECLARE @Employees TABLE
(
  ID INT PRIMARY KEY,
  Name NVARCHAR(64) NOT NULL,
  Depts VARCHAR(255) NOT NULL
);

INSERT @Departments VALUES 
  (1,'HR'),  (2,'Accts'),  (3,'IT');

INSERT @Employees VALUES
  (1,'Kevin','2,1'), (2,'Michelle','1'),
  (3,'Troy','1,3'),  (4,'Rheesa','2,3,1');

SELECT ID, Name, Depts = STUFF((SELECT ',' + d.Dept 
    FROM @Departments AS d
    INNER JOIN @Employees AS ei
    ON ',' + ei.Depts + ',' LIKE '%,' + CONVERT(VARCHAR(12), d.id) + ',%'
    WHERE ei.ID = e.ID
    ORDER BY Dept
    FOR XML PATH, TYPE).value('.[1]', 'nvarchar(max)'), 1, 1, '')
FROM @Employees AS e
ORDER BY ID;

结果与您要求的结果不太匹配，因为排序是确定性的(按部门名称排序):

The results don't quite match your required results, as the ordering is deterministic (ordered by department name):

ID      Name        Depts
----    --------    ----
1       Kevin       Accts,HR
2       Michelle    HR
3       Troy        HR,IT
4       Rheesa      Accts,HR,IT

如果您希望它们按照逗号分隔列表中的出现顺序进行排序，只需更改:

If you want them ordered by the appearance in the comma-separated list, just change:

ORDER BY Dept

收件人:

ORDER BY CHARINDEX( ',' + CONVERT(VARCHAR(12), d.id) + ',', ',' + ei.Depts + ',')

结果:

ID      Name        Depts
----    --------    ----
1       Kevin       Accts,HR
2       Michelle    HR
3       Troy        HR,IT
4       Rheesa      Accts,IT,HR -- this is the only one affected as it turns out

但是，实际上，您应该 规范化数据库 .这绝对是一场噩梦.

However, in reality, you should normalize your database. This is an absolute nightmare.

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