alter table t_apply change column remarks(原) apply_remarks(目标) varchar(100) default \'\' comment \'备注\';
alter table t_apply add column apply_order_num varchar(60) default \'\' comment \'订单号\';
alter table t_push add column push_id int auto_increment primary key comment \'push_id\'; //增加主键索引,自增
========查看所有mysql 的变量
show variables;
show variables like \'%char%\';
删除索引 主键
alter table xxx drop primary key;
alter table xxx add primary key(id);
添加索引
alter table xxx add index apply_id ( `apply_id` )