MySQL implements increasing or decreasing the specified time interval for all times in the current data table (recommended)

The DATE_ADD() function adds a specified time interval to a date.

All data in the current table will be incremented by one day:

UPDATE ACT_BlockNum SET CreateTime = DATE_ADD(CreateTime, INTERVAL 1 DAY);

All data in the current table is reduced by one day:

UPDATE ACT_BlockNum SET CreateTime = DATE_ADD(CreateTime, INTERVAL -1 DAY);

In order to prevent the database query from reporting an empty exception, when the query result is returned as an integer, it can be compared with 0. If it is empty, a 0 is returned to the customer, otherwise the result value of the query is returned. The sql is as follows

 SELECT IFNULL(SUM(Num),0) from DPEvent.ACT_BlockNum where CreateTime BETWEEN #startTime# AND #endTime#;
MYSQL IFNULL(expr1,expr2)

If expr1 is not NULL, IFNULL() returns expr1, otherwise it returns expr2. IFNULL() returns a numeric or string value, depending on the context in which it is used. Similar ones
isnull(expr)

If expr is null, then isnull() returns 1, otherwise it returns 0.

The update statement updates the values ​​of multiple fields

update @A 
set c1=b.c1 ,c2=b.c2,c3=b.c3
from @A a,@B b where a.id=2 and b.id=6
update A
  set (A.a2,A.a3) =(select B.b2,b.b3
  from B
  where B.b1= A.a1 and A.a3=100
  )

The above is what I introduced to you about MySQL to increase or decrease all the time in the current data table by a specified time interval. I hope it will be helpful to you. If you have any questions, please leave me a message and I will reply to you in time!