如何将多行组合到SQL Server 2005中以逗号分隔的列表中？

Question

现在，我有一个像这样的SQL查询：

SELECT X, Y FROM POINTS

它返回结果如下：

X    Y
----------
12   3
15   2
18   12
20   29

我想在一行中返回结果，如下所示（适合在HTML <AREA>标记中使用）：

XYLIST
----------
12,3,15,2,18,12,20,29

有没有办法只使用SQL？

Answer 1

感谢快速而有用的答案！

我刚刚找到了另一种快速方法：

SELECT  STUFF(( SELECT ',' + X + ',' + Y
                FROM Points
              FOR
                XML PATH('')
              ), 1, 1, '') AS XYList

归功于这家伙：

http://geekswithblogs.net/mnf/archive/2007/10/02/t-sql-user-defined-function-to-concatenate-column-to-csv-string.aspx

Answer 2

DECLARE @XYList varchar(MAX)
SET @XYList = ''

SELECT @XYList = @XYList + CONVERT(varchar, X) + ',' + CONVERT(varchar, Y) + ','
FROM POINTS

-- Remove last comma
SELECT LEFT(@XYList, LEN(@XYList) - 1)

Answer 3

使用COALESCE技巧，您不必担心尾随逗号：

DECLARE @XYList AS varchar(MAX) -- Leave as NULL

SELECT @XYList = COALESCE(@XYList + ',', '') + CONVERT(varchar, X) + ',' + CONVERT(varchar, Y)
FROM POINTS

Answer 4

从SQL 2017开始，您可以使用STRING_AGG

SELECT STRING_AGG (X + ',' + Y, ',') AS XYLIST
FROM POINTS

https://docs.microsoft.com/en-us/sql/t-sql/functions/string-agg-transact-sql?view=sql-server-2017

Answer 5

DECLARE @s VarChar(8000)
SET @s = ''

SELECT @s = @s + ',' + CAST(X AS VarChar) + ',' + CAST(Y AS VarChar) 
FROM POINTS

SELECT @s 

摆脱领先的逗号