个人笔记-----查询一天的开始时间和结束时间

select t.name , DATE_FORMAT(t.date,'%Y%m%d') , min(t.date) , MAX(t.date) from tttttt t group by t.name , DATE_FORMAT(t.date,'%Y%m%d');

-- 取一天的开始时间
SELECT str_to_date(DATE_FORMAT(NOW(),'%Y-%m-%d'),'%Y-%m-%d %H:%i:%s');
 
-- 取第二天的开始时间
select DATE_ADD(str_to_date(DATE_FORMAT(NOW(),'%Y-%m-%d'),'%Y-%m-%d %H:%i:%s'),INTERVAL 1 DAY)
 
-- 取一天的结束时间
select DATE_ADD(DATE_ADD(str_to_date(DATE_FORMAT(NOW(),'%Y-%m-%d'),'%Y-%m-%d %H:%i:%s'),INTERVAL 1 DAY),INTERVAL -1 SECOND);

SELECT
	demo.name,
	demo.data
FROM
	(
SELECT
	t.NAME name,
	DATE_FORMAT( t.date, '%Y%m%d' ) data,
	DATE_FORMAT( t.date, '%H' ) time 
FROM
	tttttt t 
GROUP BY
	t.NAME,
	DATE_FORMAT( t.date, '%Y%m%d' ) 
	) demo 
WHERE
	time > 21;

select de.name, count(1) from (select t.name name, DATE_FORMAT(t.date,'%Y%m%d') , min(t.date) , MAX(t.date) from tttttt t group by t.name , DATE_FORMAT(t.date,'%Y%m%d')) de;