Update a row in in the same table with the data of another row in MySQL

UPDATE biometric_image dt1, biometric_image dt2
SET dt1.cam_img = dt2.cam_img
WHERE  (dt1.comcaseno='775/2012' AND dt1.partytype='seller' AND dt1.partyserial='1') AND (dt2.comcaseno='775/2012' AND dt2.partytype='drafter' AND dt2.partyserial='1')