How to Find the Number of Days Between Two Dates in SQL

To calculate the number of days between two dates in SQL, use the DATEDIFF function. This function takes three arguments: the start date, the end date, and the unit of time you want to measure. For example, if you wanted to calculate the number of days between two dates, you would use the following query:

SELECT DATEDIFF(start_date, end_date, 'day') FROM table_name;

Examples

Let's look at a few examples of how this function can be used. Suppose you have a table called orders with the following data:

order_id  order_date
--------------------
1         2020-01-01
2         2020-01-03
3         2020-01-05

If you wanted to calculate the number of days between the first and third orders, you would use the following query:

SELECT DATEDIFF(order_date, '2020-01-05', 'day') FROM orders WHERE order_id = 1;

This query would return the result 4, since there are four days between the first and third orders.

Additional Info

The DATEDIFF function is supported by most major databases, including MySQL, PostgreSQL, and SQL Server. However, the syntax may vary slightly depending on the database you are using. For more information, check out the documentation for your particular database. 🤓