MySQL date operation (this month, last month time)

1. Description of interval:

1.1. When the function is used, that is, interval(), it is a comparison function, such as: interval(10,1,3,5,7); the result is 4;

Principle: 10 is the number to be compared, and the following 1, 3, 5, and 7 are the comparison numbers. Compare the next four with 10 in turn. See how many numbers in the following number group are less than 10, then return their number. The premise is that the following number groups are arranged from small to large, otherwise the result is 0.

1.2. When keywords are used, it means setting time interval, which is commonly used in date_add() and date_sub() functions,

For example: interval 1 day, interpreted as setting the time interval to 1 day.

3. The first day of the month

select date_add(curdate(), interval - day(curdate()) + 1 day);

今天是当月的第几天：SELECT DAYOFMONTH( NOW());

4. The last day of the month

select last_day(curdate());

5. The first day of last month

select date_add(curdate()-day(curdate())+1,interval -1 month);

6. Last day of last month

select last_day(date_sub(now(),interval 1 month));

7. The first day of next month

select date_add(curdate()-day(curdate())+1,interval 1 month);

8. The last day of next month

select last_day(date_sub(now(),interval -1 month));

9. Number of days in the month

select day(last_day(curdate()));

10. The current date of last month and today

select date_sub(curdate(), interval 1 month);

11. The current time of the previous month and today (time stamp)

select unix_timestamp(date_sub(now(),interval 1 month));

12. Get the number of days between the current time and the previous month

select datediff(curdate(), date_sub(curdate(), interval 1 month));

13, today

SELECT DATE_FORMAT(NOW(),'%Y-%m-%d 00:00:00') AS '今天开始';
SELECT DATE_FORMAT(NOW(),'%Y-%m-%d 23:59:59') AS '今天结束';

14, yesterday

SELECT DATE_FORMAT( DATE_SUB(CURDATE(), INTERVAL 1 DAY), '%Y-%m-%d 00:00:00') AS '昨天开始';
SELECT DATE_FORMAT( DATE_SUB(CURDATE(), INTERVAL 1 DAY), '%Y-%m-%d 23:59:59') AS '昨天结束';

15. Last week

SELECT DATE_FORMAT( DATE_SUB( DATE_SUB(CURDATE(), INTERVAL WEEKDAY(CURDATE()) DAY), INTERVAL 1 WEEK), '%Y-%m-%d 00:00:00') AS '上周一';
SELECT DATE_FORMAT( SUBDATE(CURDATE(), WEEKDAY(CURDATE()) + 1), '%Y-%m-%d 23:59:59') AS '上周末';

16. This week

SELECT DATE_FORMAT( SUBDATE(CURDATE(),DATE_FORMAT(CURDATE(),'%w')-1), '%Y-%m-%d 00:00:00') AS '本周一';
SELECT DATE_FORMAT( SUBDATE(CURDATE(),DATE_FORMAT(CURDATE(),'%w')-7), '%Y-%m-%d 23:59:59') AS '本周末';

-- 上面的本周算法会有问题,因为mysql是按照周日为一周第一天,如果当前是周日的话,会把时间定为到下一周.
SELECT DATE_FORMAT( DATE_SUB(CURDATE(), INTERVAL WEEKDAY(CURDATE()) DAY), '%Y-%m-%d 00:00:00') AS '本周一';
SELECT DATE_FORMAT( DATE_ADD(SUBDATE(CURDATE(), WEEKDAY(CURDATE())), INTERVAL 6 DAY), '%Y-%m-%d 23:59:59') AS '本周末';

17, first month

SELECT DATE_FORMAT( DATE_SUB(CURDATE(), INTERVAL 1 MONTH), '%Y-%m-01 00:00:00') AS '上月初';
SELECT DATE_FORMAT( LAST_DAY(DATE_SUB(CURDATE(), INTERVAL 1 MONTH)), '%Y-%m-%d 23:59:59') AS '上月末';

18. This month

SELECT DATE_FORMAT( CURDATE(), '%Y-%m-01 00:00:00') AS '本月初';
SELECT DATE_FORMAT( LAST_DAY(CURDATE()), '%Y-%m-%d 23:59:59') AS '本月末';

19. The first day of the year

SELECT DATE_SUB(CURDATE(),INTERVAL dayofyear(now())-1 DAY)  

或

concat(year(now()),'-01-01')//当前年份的第一天
concat(year(now()),'-12-31')//当前年份的最后一天

20. Time difference conversion

SELECT 
	TIME_TO_SEC(TIMEDIFF('2018-09-30 19:38:45', '2018-08-23 10:13:01')) AS DIFF_SECOND1, -- 秒
	UNIX_TIMESTAMP('2018-09-30 19:38:45')-UNIX_TIMESTAMP('2018-08-23 10:13:01') AS DIFF_SECOND2, -- 秒
	TIMESTAMPDIFF(SECOND,'2018-08-23 10:13:01','2018-09-30 19:38:45') AS DIFF_SECOND3, -- 秒
	TIMESTAMPDIFF(MINUTE,'2018-08-23 10:13:01','2018-09-30 19:38:45') AS DIFF_MINUTE, -- 分
	TIMESTAMPDIFF(HOUR,'2018-08-23 10:13:01','2018-09-30 19:38:45') AS DIFF_HOUR, -- 小时
	TIMESTAMPDIFF(DAY ,'2018-08-23 10:13:01','2018-09-30 19:38:45') AS DIFF_DATE1, -- 天
	DATEDIFF('2018-09-30 19:38:45','2018-08-23 10:13:01') AS DIFF_DATE2, -- 天
	TIMESTAMPDIFF(MONTH,'2018-08-23 10:13:01','2018-09-25 19:38:45') AS DIFF_MONTH, -- 月
	TIMESTAMPDIFF(YEAR,'2018-08-23 10:13:01','2020-07-25 19:38:45') AS DIFF_YEAR -- 年
FROM DUAL;

21. The date adds year, month, day, hour, minute, and second

select date_add(日期, interval 1 day); 日期加天
select date_add(日期, interval 1 hour); 日期加小时
select date_add(日期, interval 1 minute); 日期加分
select date_add(日期, interval 1 second);日期加秒
select date_add(日期, interval 1 microsecond); 日期加微秒
select date_add(日期, interval 1 week); 日期加周
select date_add(日期, interval 1 month); 日期加月
select date_add(日期, interval 1 quarter); 日期加季度
select date_add(日期, interval 1 year); 日期加年

22. All days in the current month cycle (input date is automatically converted to the number of days in the current month) 

SELECT ADDDATE(y.first, x.d - 1) as d 
FROM (
	SELECT 1 AS d UNION ALL
	SELECT 2 UNION ALL
	SELECT 3 UNION ALL
	SELECT 4 UNION ALL
	SELECT 5 UNION ALL
	SELECT 6 UNION ALL
	SELECT 7 UNION ALL
	SELECT 8 UNION ALL
	SELECT 9 UNION ALL
	SELECT 10 UNION ALL
	SELECT 11 UNION ALL
	SELECT 12 UNION ALL
	SELECT 13 UNION ALL
	SELECT 14 UNION ALL
	SELECT 15 UNION ALL
	SELECT 16 UNION ALL
	SELECT 17 UNION ALL
	SELECT 18 UNION ALL
	SELECT 19 UNION ALL
	SELECT 20 UNION ALL
	SELECT 21 UNION ALL
	SELECT 22 UNION ALL
	SELECT 23 UNION ALL
	SELECT 24 UNION ALL
	SELECT 25 UNION ALL
	SELECT 26 UNION ALL
	SELECT 27 UNION ALL
	SELECT 28 UNION ALL
	SELECT 29 UNION ALL
	SELECT 30 UNION ALL
	SELECT 31
) x,
(
	SELECT '2019-09-05' - INTERVAL DAY('2019-09-05') - 1 DAY AS first, DAY(LAST_DAY('2019-09-05')) AS last 
) y
WHERE x.d <= y.last

23. Simulate 12-month dates

SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-01-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-01-31'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-02-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-02-28'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-03-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-03-31'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-04-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-04-30'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-05-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-05-31'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-06-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-06-30'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-07-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-07-31'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-08-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-08-31'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-09-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-09-30'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-10-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-10-31'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-11-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-11-30'),'%Y-%m-%d') END_V
UNION
SELECT STR_TO_DATE(CONCAT(YEAR(now()),'-12-01'),'%Y-%m-%d') BEGIN_V,STR_TO_DATE(CONCAT(YEAR(now()),'-12-31'),'%Y-%m-%d') END_V

24、

    #当年第一天：  
    SELECT DATE_SUB(CURDATE(),INTERVAL dayofyear(now())-1 DAY);  
      
    #当年最后一天：  
    SELECT concat(YEAR(now()),'-12-31');    
      
    #当前week的第一天：    
    select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 1 DAY);  
      
    #当前week的最后一天：    
    select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) - 5 DAY);  
      
    #前一week的第一天：    
    select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 8 DAY);  
      
    #前一week的最后一天：    
    select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 2 DAY);  
      
    #前两week的第一天：    
    select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 15 DAY);  
      
    #前两week的最后一天：    
    select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 9 DAY);  
      
    #当前month的第一天：    
    SELECT concat(date_format(LAST_DAY(now()),'%Y-%m-'),'01');  
      
    #当前month的最后一天：    
    SELECT  LAST_DAY(now());  
      
    #前一month的第一天：    
    SELECT concat(date_format(LAST_DAY(now() - interval 1 month),'%Y-%m-'),'01');  
      
    #前一month的最后一天：    
    SELECT LAST_DAY(now() - interval 1 month);  
      
    #前两month的第一天：    
    SELECT concat(date_format(LAST_DAY(now() - interval 2 month),'%Y-%m-'),'01');  
      
    #前两month的最后一天：    
    SELECT  LAST_DAY(now() - interval 2 month);  
      
    #当前quarter的第一天：    
    select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM  CURDATE()),1) + interval QUARTER(CURDATE())*3-3 month),'%Y-%m-'),'01');   
      
    #当前quarter的最后一天：    
    select LAST_DAY(MAKEDATE(EXTRACT(YEAR  FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-1 month);  
      
    #前一quarter的第一天：    
    select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-6 month),'%Y-%m-'),'01');  
      
    #前一quarter的最后一天：    
    select  LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-4 month);  
      
    #前两quarter的第一天：    
    select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-9 month),'%Y-%m-'),'01');  
      
    #前两quarter的最后一天：    
    select LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-7 month);