Total Credits without Sort Codes, by Primary Provider

SELECT
 r.provcode,
 r.provlname,
 SUM(j.amount)
FROM
 sos.journal j
 JOIN sos.patients p on j.ptnum=p.ptnum
 JOIN sos.providers r on p.providernum=r.providernum
WHERE
 j.trandate BETWEEN '2000-03-01' AND '2016-03-15' AND
 j.sortcode IS NULL
GROUP BY
 r.provcode, r.provlnamee