MERGE INTO vws_art_alert
USING (
   SELECT rin_date_unreg, rin_per_id
   FROM vwe_cpr_info
   WHERE rin_date_unreg >= '27-SEP-11'
   AND rin_date_unreg <= '13-JAN-12')
ON (vws_art_alert.art_per_id = vwe_cpr_info.rin_per_id
    AND art_alert = 'AL02'
    AND art_inactive_on IS NULL)
WHEN MATCHED THEN
UPDATE SET vws_art_alert.art_inactive_on = vwe_cpr_info.rin_date_unreg;

MERGE INTO vws_art_alert
USING (
   SELECT rin_date_unreg, rin_per_id
   FROM vwe_cpr_info
   WHERE rin_date_unreg >= '27-SEP-11'
   AND rin_date_unreg <= '13-JAN-12') t
ON (vws_art_alert.art_per_id = vwe_cpr_info.rin_per_id
    AND art_alert = 'AL02'
    AND art_inactive_on IS NULL)
WHEN MATCHED THEN
UPDATE SET vws_art_alert.art_inactive_on = t.rin_date_unreg;