UPDATE 
pcase_litigant pl1
INNER JOIN pcase_litigant_new pl2 ON pl1.run_id = pl2.run_id AND pl1.lit_type = pl2.lit_type
AND pl1.ref_litigantcode = pl2.ref_litigantcode
SET pl1.new_seq=pl2.seq
WHERE  pl1.seq != pl2.seq