WITH DOCS AS (
    SELECT COUNT(dm.DOCNUM) AS DocCount, dm.C2ALIAS
    FROM MHGROUP.DOCMASTER dm WITH (nolock)
    GROUP BY dm.C2ALIAS)
SELECT DOCS.DocCount, c2.C_DESCRIPT AS MatterNum
FROM DOCS
    LEFT JOIN MHGROUP.CUSTOM2 c2 WITH (nolock) ON DOCS.C2ALIAS = c2.CUSTOM_ALIAS
ORDER BY DOCS.DocCount DESC