• 查询某年的数据

 select * from oa_item_info where created like '2018-%';

select * from oa_item_info where left(created,4)='2018';

select * from oa_item_info where year(created)='2018';

• 今年的数据：

select * from oa_item_info where year(created)=year(now());

• 上一年的数据：

select * from oa_item_info where year(created)=year(date_sub(now(),interval 1 year));

select QUARTER(created)  as quartername ,created from oa_item_info ;

先看一下quarter函数返回的数据，第一列是quartername,第二列是created

1-3月返回1，4-6月返回2,7到9月返回3,10到12月返回4

并不是搜索本季度的数据：

select * from oa_item_info where QUARTER(created)=QUARTER(now());

这条sql语句返回的是所有年份，当前季度的数据，比如现在是4月，会把所有年份4到6月的数据都检索出来

搜索本季度的数据：

加上本年的限制条件

 select * from oa_item_info where QUARTER(created)=QUARTER(now()) and year(created)=year(now());

 select month(created) as monthname,created from oa_item_info；

看一下返回数据：第一列是monthname,第二列是created

所有年份2月的数据

 select * from oa_item_info where month(created)=2；

加上年份的限定条件就可以了

查询某周的数据

select week(created) as weekname,created from oa_item_info ;

看一下返回数据：第一列是weekname,第二列是created

返回的是一年中的第几周

本周的数据：

 select  created   from oa_item_info where week(created)=week(now()) and year(created)=year(now());

select * from oa_item_info where YEARWEEK(date_format(created,'%Y-%m-%d')) = YEARWEEK(now()) ；

看一下week和yearweek的区别：

数据库中加入两条周数一致的日期：

看一下yearweek的返回值：

看一下搜索结果：

select  created   from oa_item_info where week(created)=week(now());

week把两条年份不一样的都搜出来了

 select created  from oa_item_info where YEARWEEK(date_format(created,'%Y-%m-%d')) = YEARWEEK(now()) ;

select created  from oa_item_info where YEARWEEK(created) = YEARWEEK(now()) ;

不用date_format函数也可以

yearweek只搜出了今天的

未完