Mysql date and time-related functions

Directory:

1. Common date functions
2. Time-plus-decrement function
3. Date_forma function

1. Common date functions

Now () Current_timestamp () sysdate ()

• Example one:

　　

You can see that three functions are used to get the current system time.

• Example two:

　　

In the operation, the sleep function was added, waiting for 2 seconds, then found that the Sysdate function and the other two functions to get the value of different, sysdate function to get the value of 2 seconds faster. So three functions are slightly different, the difference is as follows:

• Current_timestamp and now are synonyms, and the two are the same.

• The Sysdate function returns the time it takes to execute to the current function, and now returns the time when the SQL statement was executed.

2. Time-plus-decrement function

Date_add (date, interval expr unit) date_sub (date, interval expr unit)

• Example one:

　　

The value of expr can be positive or negative, so you can use the Date_add function to do the work of the Date_sub function, for example:
　　
　　

• Example two:

　　

In the above example, the unit parameter uses day, hour, in fact, you can also use microsecond, second, minute, week, month, year and other types.

3. Date_format function

• Example one:　

Select ' %y%m%d '  as DateTime;

Operation Result:

　　

　　

Mysql date and time-related functions