Comparing datetime values in SQL server 2008

Question

I'm facing a challenge in comparing datetime values in SQL server 2008.

I want to select only those rows from the table 'Plane_Allocation_Table' where the column 'To_Date' which is of type DATETIME is less than today's date and time (which I obtained using GETDATE()). And update two tables depending on the Values the above query returns.

However, the queries I tried don't return any rows.

The last stored procedure I worte looks like :

-- Procedure to Update Total_Allocation in Hanger_Details and Validity of Booking in Plane_Allocation_Details :

CREATE PROCEDURE [dbo].[Update_Total_Allocation_APMS]
AS
DECLARE @now DATETIME
SELECT @now = GETDATE()
UPDATE Hanger_Details
SET Total_Allocation = Total_Allocation - 1
WHERE Hanger_Number IN
(
    SELECT Hanger_Number
    FROM Plane_Allocation_Details
    WHERE To_Date <= @now AND Validity = 'Valid'
)
UPDATE Plane_Allocation_Details
SET Validity = 'Not Valid'
WHERE To_Date <= @now

The comparison of 'To_Date' and '@now' isn't working. Is there any solution to comparing datetime values from a table in a stored procedure?

PS : Please note that I want to make the comparison on the basis of date as well as time. For instance, if the time datetime is '2014-12-20 10:00:00.000' now, and the column value is '2014-12-20 09:59:00.000' then the row must be returned.

Edit1 : I've corrected the typo there. (=< to <=)

Answer 1

You can cast the datetime values to date-only values.

e.g.

DECLARE @today date
SELECT @today = CONVERT(date, GETDATE())

UPDATE Plane_Allocation_Details
SET Validity = 'Not Valid'
WHERE CONVERT(date, To_Date) <= @today