In MariaDB, the SYSDATE() and NOW() functions are similar in that they return the current date and time.

However, there is an important difference: SYSDATE() returns the time that it executes, whereas NOW() returns the time that the statement started executing.

And when run within a stored procedure or trigger, SYSDATE() will return the time that it executes, whereas NOW() will return the time that the stored procedure or trigger started executing.

Example

First, let’s look at how these two functions can produce different results.

SELECT 
    NOW(),
    SYSDATE(),
    SLEEP(5),
    NOW(),
    SYSDATE();

Result (using vertical output):

    NOW(): 2021-05-27 09:22:08
SYSDATE(): 2021-05-27 09:22:08
 SLEEP(5): 0
    NOW(): 2021-05-27 09:22:08
SYSDATE(): 2021-05-27 09:22:13

Here, we used the SLEEP() function to pause processing for five seconds before the second lot of function calls.

We can see that the second time SYSDATE() was invoked, its return value was different to the first time. NOW() on the other hand, returned the same value both times.

Other Considerations

There are a few other things to be mindful of with these two functions:

• SET TIMESTAMP doesn’t affect SYSDATE(), whereas it does affect the NOW() function.
• SYSDATE() is unsafe for replication if statement-based binary logging is used. However, there are ways to deal with this, if required. You can use --sysdate-is-now command is a non-default option to alias SYSDATE() to NOW() to make it safe for replication. See the MariaDB documentation for SYSDATE() for more information.