DATEDIFF
Subtracts to find the number of days between two dates.
Syntax
DATEDIFF(date1, date2)
Arguments
date1, date2: a valid date, datetime, or parsable date string. Only the date part is used.
Return Type
Integer. If date1 or date2 is not a valid date, returns NULL.
Examples
SELECT DATEDIFF('2017-03-27', '2017-03-26') AS days_til_graduation;
****
+---------------------+
| days_til_graduation |
+---------------------+
| 1 |
+---------------------+
If date1 is in the past, the function returns a negative result.
SELECT DATEDIFF('2017-03-26', '2017-03-27') AS days_til_graduation;
****
+---------------------+
| days_til_graduation |
+---------------------+
| -1 |
+---------------------+
NOW() can be used as one of the parameters.
SELECT DATEDIFF('2099-12-31', NOW()) AS days_til_graduation;
****
+---------------------+
| days_til_graduation |
+---------------------+
| 30229 |
+---------------------+