将行值分组为逗号分隔的列表

Question

  

可能重复：
  SQL Query to get aggregated result in comma seperators along with group by column in SQL Server

我有两张桌子：

CarID | CarName  | Color  
------+----------+----------
1     | Ford     | White  
2     | Mitsu    | Black  
3     | Mitsu    | Green  

OwnerID | OwnerName | CarID  
--------+-----------+-------
1       | John      | 1  
1       | John      | 3  
2       | Mark      | 2  

我需要一份以下报告：

CarName | Owners  
--------+------------
Ford    | John  
Mitsu   | John, Mark  

怎么可能呢？

Answer 1

在数据库级别构建正确的数据集最容易，例如：

SELECT
    c.CarName,
    STUFF
    (
        (
            SELECT ',' + owner
            FROM Owner o
            WHERE c.carID = o.carID
            ORDER BY owner
            FOR XML PATH('')
        ), 1, 1, ''
    ) AS owners
FROM Car c

这将为每个汽车/颜色组合返回一行，因此还需要考虑的是是否要忽略颜色 - 然后您需要对汽车名称进行分组：

SELECT
    c.CarName,
    STUFF
    (
        (
            SELECT ',' + owner
            FROM (select cd.carname, o.owner from Owner o inner join Car cd on o.carID = cd.carID) o
            WHERE c.CarName = o.CarName
            ORDER BY owner
            FOR XML PATH('')
        ), 1, 1, ''
    ) AS owners
FROM (select distinct carname from Car) c

一旦您获得了正确的数据集，只需创建一个简单的表来显示结果。