mysql优化 - mysql如何优化这条更新语句？

问题描述

问题解答

UPDATE yw_tmp_usr a, yhdang b SET a.hth = b.hth WHERE a.business_key=b.dh

UPDATE yw_tmp_usr SET hth = T.hth

FROM (

SELECT hth, dh FROM yhdang

) T

WHERE yw_tmp_usr.business_key = T.dh