How can I combine multiple rows into a comma-delimited list in SQL Server 2005?

Question

Right now, I have a SQL Query like this one:

SELECT X, Y FROM POINTS

It returns results like so:

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

I'd like to return results all in one row, like this (suitable for using in an HTML <AREA> tag):

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

Is there a way to do this using just SQL?

Answer 1

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

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

SELECT @s

Just get rid of the leading comma

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

Thanks for the quick and helpful answers guys!

I just found another fast way to do this too:

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

Credit goes to this guy:

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

Answer 4

Using the COALESCE trick, you don't have to worry about the trailing comma:

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

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