MS SQL compare dates?

sql-server tsql sql-server-2008 date
grady picture grady · Jan 25, 2011 · Viewed 208.9k times · Source

I have 2 dates (datetimes):

date1 = 2010-12-31 15:13:48.593
date2 = 2010-12-31 00:00:00.000

Its the same day, just different times. Comparing date1 and date2 using <= doesnt work because of the date1 time. So date1 <= date2 is wrong, but should be true. Can I compare them by just looking at the year, month and day so they are the same? Its SQL Server 2008.

Thanks :)

Answer

Martin Smith picture Martin Smith · Jan 25, 2011 
SELECT CASE WHEN CAST(date1 AS DATE) <= CAST(date2 AS DATE) ...

Should do what you need.

Test Case

WITH dates(date1, date2, date3, date4)
     AS (SELECT CAST('20101231 15:13:48.593' AS DATETIME),
                CAST('20101231 00:00:00.000' AS DATETIME),
                CAST('20101231 15:13:48.593' AS DATETIME),
                CAST('20101231 00:00:00.000' AS DATETIME))
SELECT CASE
         WHEN CAST(date1 AS DATE) <= CAST(date2 AS DATE) THEN 'Y'
         ELSE 'N'
       END AS COMPARISON_WITH_CAST,
       CASE
         WHEN date3 <= date4 THEN 'Y'
         ELSE 'N'
       END AS COMPARISON_WITHOUT_CAST
FROM   dates

Returns

COMPARISON_WITH_CAST   |  COMPARISON_WITHOUT_CAST
Y                         N

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