PHP去除字符串中数字的方法:方法简单,代码为:$class=preg_replace("\\d+",'', $res);需要使用preg_replace函数,但是只是这么写的话,会报错Warning: preg_replace(): Delimiter must not be alphanumeric or&
mysql数据库去除重复数据的方法:1、查询需要删除的记录,会保留一条记录。select a.id,a.subject,a.RECEIVER from test1 a left join (select c.subject,c.RECEIVER ,max(c.id) as bid from test1 c