Function

DATEDIFF

Calculates the number of days between the two parameters. In this example the function returns

12

which is the number of days between the dates

SELECT 
    DATEDIFF('2021-03-25', '2021-03-13')

The function returns

negative number

if the second date is greater than the first one. In the example the result will be

-12

SELECT 
    DATEDIFF('2021-03-13', '2021-03-25')