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
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