mysql sql语句求助

[宝宝很6]

sql太渣 ，想要实现如下功能：
当 SELECT COUNT(*) c FROM t_borrow w WHERE w.`status`=0 AND w.flag=0 AND w.fuid IS NULL AND (UNIX_TIMESTAMP(NOW())-UNIX_TIMESTAMP(w.adtime))>48*3600 查询查来的条数>0时，执行一条sql : UPDATE t_member m SET m.`currentlimit`= m.`currentlimit`+(SELECT b.`money` FROM t_borrow b WHERE b.`status`=0 AND flag=0 AND b.fuid IS NULL AND (UNIX_TIMESTAMP(NOW())-UNIX_TIMESTAMP(b.adtime))>48*3600 AND b.`uid`=m.`id`) WHERE b.`uid`=IN (SELECT w.`uid` FROM t_borrow w WHERE w.`status`=0 AND flag=0 AND w.fuid IS NULL AND (UNIX_TIMESTAMP(NOW())-UNIX_TIMESTAMP(w.adtime))>48*3600)
否则不执行，请问该怎么写