以其他字段作为某一字段的值. 字段长度char

UPDATE t_dealer a INNER JOIN t_dealer b ON a.id=b.id SET a.zihao=b.shortName where a.zihao is null or a.zihao='' and char_length(a.shortName)<=20

转载于:https://www.cnblogs.com/yanjunwu/p/4021364.html