有时需要将日期类型值转换成毫秒值，有时也要将毫秒值转换成日期，为了更方便，满足查询的需要。
现在，新建一张数据库表t_stu_info，并向表里插入数据
use test;show tables;create table t_stu_info( id int not null primary key, stu_name varchar(20), stu_date timestamp, stu_age int(3), stu_sex varchar(5) ); insert into t_stu_info(id,stu_name,stu_date,stu_age,stu_sex) values ('1','zhangsan','2000-12-12 12:30:00','15','man');commit;select * from t_stu_info;
1、日期转换成毫秒值
select UNIX_TIMESTAMP(t.stu_date) from t_stu_info t
2、毫秒值转换成日期
SELECT FROM_UNIXTIME(UNIX_TIMESTAMP(t.stu_date), '%Y-%m-%d %h:%i:%s') AS stu_dateFROM t_stu_info t
SELECT FROM_UNIXTIME(UNIX_TIMESTAMP(t.stu_date), '%Y-%m-%d') AS stu_dateFROM t_stu_info t
