在MYSQL中，日期类型为 DATETIME 数据格式为： 2009-05-25 12:11:05
1. MySQL 官方tutorial
11.6. Date and Time Functions
Link: http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_adddate
2. MySQL DATE_ADD() Function
Link: http://www.w3schools.com/SQL/func_date_add.asp
-----------------------------------------------例子--------------------------------------------------------
问题1：搜索2007-08-25 的记录
select * from table where dt='2007-08-25'问题2：搜索2007-08-01到2007-08-15的所有记录
select * from table where dt between '2007-08-01' and '2007-08-15'between '2007-08-01' and '2007-08-15' 对该表中的dt仅能找出 2007-08-01 0:0:0 到 2007-08-15 0:0:0 之间的要实现具体的，自己修改修改
问题3：找出当前的日期减一天，或是减一个月
select * from table where abs(datediff(dt,current_timestamp))<=1 --前后一天内的 select * from table where period_diff(DATE_FORMAT(current_timestamp,'%Y%m'),DATE_FORMAT(dt,'%Y%m'))<1--------------------------------------------------------------------------------------------------------------
