TSQL Comma Separation

Question

I\'m writing an export function, where I need to export contacts to Excel, and I\'ve run into a technical snag - or perhaps a gap in my SQL skills is closer to the truth. ;)

Answer 1

You can do it in a single query, though I don't know if the performance is good or bad.

SELECT [<group field 1>], [<group field 2>], [etc...], (
    SELECT CAST([<field to list>] AS VARCHAR(MAX)) + 
        CASE WHEN (ROW_NUMBER() OVER (ORDER BY [<inner order-by REVERSED>]) = 1)
            THEN '' ELSE ',' END
        AS [text()]
    FROM [<inner table>]
    WHERE [<inner table join field>] = [<outer table join field>]
    AND [<inner conditions>]
    ORDER BY [<inner order-by>]
    FOR XML PATH('')) AS [<alias>]
FROM [<outer table]
WHERE [<outer conditions>]

That CASE statement inside is just to remove the last comma from the list--you have to ORDER BY something for the inner query and then reverse that ORDER BY in the CASE statement.