The **`DATEDIFF()` function** returns the *number of days* between two dates sent as parameter. 

Figure 1 shows a visual representation of the `DATEDIFF()` function.

# Syntax
```sql
DATEDIFF(date-1, date-2)
```
# Parameter
The `DATEDIFF()` function takes `two dates` as a parameter. 
> Dates must be in the format YYYY-MM-DD, or  this function returns `NULL`.

# Return value
The `DATEDIFF()` function returns the *number of days* between two dates sent as a parameter. 
> This function only uses the *date* portion if the datetime is sent instead of date.


# Example




-- date1>date2
SELECT DATEDIFF('2021-07-10','2021-07-09');

-- date1<date2
SELECT DATEDIFF('2021-07-10','2021-07-12');

-- datetime 
SELECT DATEDIFF('2021-07-10 07:15:11','2021-07-09 09:24:31');

-- date in wrong format
SELECT DATEDIFF('10-07-2021','09-07-2021');


What is DATEDIFF() in SQL?

The DATEDIFF() function returns the number of days between two dates sent as parameter. Figure 1 shows a visual representation of the DATEDIFF() function. 