MySql常用日期时间查询

-- 某一天所在周的第一天：
-- 我们知道国外的星期的第一天是从星期天开始的，所以DAYOFWEEK('2017-3-10')函数的第一天是星期天：
SELECT
CASE WHEN DAYNAME(DATE('2017-3-10'))='Sunday'
THEN DATE_SUB(DATE('2017-3-10'),INTERVAL 6 DAY)
ELSE DATE_ADD('2017-3-10',INTERVAL -DAYOFWEEK(DATE('2017-3-10'))+2 DAY) END

-- 某一天所在周的最后一天：
SELECT CASE WHEN DAYNAME(DATE('2017-3-11'))='Sunday' THEN DATE('2017-3-11') ELSE DATE_ADD('2017-3-11',INTERVAL 7-DAYOFWEEK('2017-3-11')+1 DAY) END

-- 某一天的所在月的第一天：
SELECT DATE_ADD( DATE_ADD(LAST_DAY('2017-03-03'),INTERVAL 1 DAY ),INTERVAL -1 MONTH );

-- 或
SELECT DATE_SUB(DATE_ADD(LAST_DAY('2017-03-03'),INTERVAL 1 DAY),INTERVAL 1 MONTH)

-- 或
SELECT DATE_SUB(LAST_DAY('2017-03-03'),INTERVAL TIMESTAMPDIFF(DAY,'2017-03-03',(DATE_ADD('2017-03-03',INTERVAL 1 MONTH)))-1 DAY)

-- 某一天所在月的最后一天：
SELECT LAST_DAY('2017-03-03'); 

select DATE_FORMAT(NOW(),'%Y-%m-%d %h:%i:%s');

-- 某一天所在月的天数：
SELECT TIMESTAMPDIFF(DAY,'2017-03-03',(DATE_ADD('2017-03-03',INTERVAL 1 MONTH)));

set @dt = now();
select date_add(@dt, interval 1 day);   - 加1天
select date_add(@dt, interval 1 hour);   -加1小时
select date_add(@dt, interval 1 minute);    - 加1分钟
select date_add(@dt, interval 1 second); -加1秒
select date_add(@dt, interval 1 microsecond);-加1毫秒
select date_add(@dt, interval 1 week);-加1周
select date_add(@dt, interval 1 month);-加1月
select date_add(@dt, interval 1 quarter);-加1季
select date_add(@dt, interval 1 year);-加1年  

select TIMESTAMPDIFF(DAY,'2019-06-01','2019-06-05');

select DATE_FORMAT('20190606','%Y-%m-%d');

-- 遍历指定时间段集合
select t.date from (
SELECT DATE_FORMAT(DATE_ADD(date_sub('2019-06-01',INTERVAL 1 day), INTERVAL num DAY), '%Y-%m-%d') as date
FROM (
	SELECT @num:=@num+1 as num from
	(SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) a,
	(SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) b,
	(SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) c,
	(SELECT 1 UNION SELECT 2 UNION SELECT 3 ) d,
	(SELECT @num:=0) m
) x)t where t.date<='2019-12-01';

-- 遍历指定时间段集合2
select a.date,DAYOFWEEK(a.date)-1,WEEKDAY(a.date)+1,DAYNAME(DATE(a.date)) from
(
select @num:=@num+1,
date_format(adddate(date_sub('2020-01-02',INTERVAL 1 day),INTERVAL @num day),'%Y-%m-%d') as date
from t_student,
(select @num:=0) t
where ADDDATE('2020-01-02',INTERVAL @num day)<= date_format('2020-03-01','%Y-%m-%d')
) a;