SQL query to check if a date is close to today

Here's a table:

orders(id, item, deliveryDate, courier_id)

I'd like to write a query that will return all orders for a given courier with a delivery date that's within a month of toda开发者_JS百科y. How do I do that?

Most servers use the integer part of the date for days.

In this example I use "Now()" as a server function that returns the current date. You should look the right one on the documentation of the server you use.

(also the ? mark as the value of courier id)

Select * 
From orders
Where Now() - deliveryDate < 30
And courier_id = ?

If your server does not hold days - you can look on it's date-conversion functions

In T-SQL:

SELECT *
FROM orders
WHERE deliveryDate BETWEEN GETDATE() AND GETDATE() + 30
  AND courier_id = @CourierID

EDIT

While the period in this solution is calculated to be roughly a month, it is not precisely one month, as uncle brad has neatly observed. If you need to be precise, you should calculate one month from the current date like this: DATEADD(month, 1, GETDATE()). This replaces GETDATE() + 30 in the above query.

If MySQL

DATE_ADD

SELECT * FROM orders WHERE deliveryDate BETWEEN NOW() AND DATE_ADD(NOW(), INTERVAL 1 MONTH);