When creating a report often the date column provides more detail than we need to see. Here is a handy little UDF that rounds a DATETIME column to either the MINUTE, HOUR, DAY, WEEK or MONTH.

DateFirst UDF

IF OBJECT_ID('dbo.udfDateFirst') IS NOT NULL
    DROP FUNCTION dbo.udfDateFirst
GO
CREATE FUNCTION dbo.udfDateFirst
(
    @interval    VARCHAR(10),
    @rawDate    DATETIME
)
RETURNS DATETIME
AS
BEGIN    
    -- Remove seconds for allintervals
    SET @rawDate = CAST(@rawDate AS SMALLDATETIME)

    IF @interval = 'MINUTE'        
        RETURN @rawDate
    ELSE -- strip off minutes
        SET @rawDate = DATEADD(minute,-1 * DATEPART(minute,@rawDate),@rawDate)

    IF @interval = 'HOUR'        
        RETURN @rawDate
    ELSE -- strip off hours
        SET @rawDate = DATEADD(hour, -1 * DATEPART(hour,@rawDate),@rawDate)

    IF @interval = 'DAY'
        RETURN @rawDate

    IF @interval = 'WEEK'
        RETURN DATEADD(day, -1 * DATEPART(weekday,@rawDate),@rawDate)

    -- move date to first of month
    SET @rawDate = DATEADD(day, -1 * DATEPART(day,@rawDate) + 1,@rawDate)

    IF @interval = 'MONTH'
        RETURN @rawDate
    
    -- move Date to first of year
    SET @rawDate = DATEADD(month, -1 * DATEPART(month,@rawDate)+1 , @rawDate)

    RETURN @rawDate
    
END

Test Query

DECLARE @now AS DATETIME
SET @now = getDate()

SELECT dbo.udfDateFirst('MINUTE',@now)
SELECT dbo.udfDateFirst('HOUR',@now)
SELECT dbo.udfDateFirst('DAY',@now)
SELECT dbo.udfDateFirst('WEEK',@now)
SELECT dbo.udfDateFirst('MONTH',@now)
SELECT dbo.udfDateFirst('YEAR',@now)

Labels: Dates, SQL, UDF