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sql-serverdatedatetimecastingcomparison

What happens when you do a comparison "date <= datetime" in SQL-server?

What happens when you do a comparison "date <= datetime" in SQL-server?

Are they both cast to date or are they both cast to datetime in order to do the comparison?

Solution

  • datetime has higher precedence than date so the date will be cast to datetime.

    This is documented here.

    Or you can also see this below

    DECLARE @D DATETIME = '2022-09-15 11:59:59';

SELECT CASE WHEN @D = CAST(@D AS DATE) THEN 'Equal' ELSE 'NotEqual' END

    (Returns "NotEqual". If the implicit casting was to date and the time portion removed both would be equal)