prøv dette:
SELECT City_Code,
Post_Code =
STUFF((SELECT ', ' + Post_Code
FROM your_table b
WHERE b.City_Code = a.City_Code
FOR XML PATH('')), 1, 2, ''),
Post_Code_Description=
STUFF((SELECT ', ' + Post_Code_Description
FROM your_table b
WHERE b.City_Code = a.City_Code
FOR XML PATH('')), 1, 2, '')
FROM your_table a
GROUP BY City_Code