DATEDIFF Function - SQL
Overview
The DATEDIFF function in SQL returns the difference in days between two dates. It is useful for calculating the number of days between two date expressions.
Example:
SELECT
DATEDIFF('2024-01-11', '2024-01-01')
Syntax:
SELECT
DATEDIFF(end_date, start_date)
end_date is the later date.
start_date is the earlier date.
Sample Data:
| first_name | birthday |
|---|---|
| Frank | 1994-03-15 00:00:00 |
| Jane | 1980-06-14 00:00:00 |
| Ashley | 1975-12-05 00:00:00 |
| Glenn | 1988-03-23 00:00:00 |
| Kelly | 1979-10-11 00:00:00 |
| Richard | 1985-08-30 00:00:00 |
| George | 1992-02-18 00:00:00 |
| Kyle | 1983-04-07 00:00:00 |
| James | 1978-09-27 00:00:00 |
| Gustavo | 1987-11-21 00:00:00 |
Example: Hard-coded value
In this example, we are returning the difference between the date ‘2024-01-11’ and ‘2024-01-01,’ the final output is 10.
Example: Query without the WHERE Statement
In this example, we are returning the difference between the birthday column and the ‘2024-01-01’ date.
Example: Query with the WHERE Statement
In this example, we are returning the difference between the birthday column and the ‘2024-01-01’ date where the first_name column equals ‘Kelly.’
