Author Message Stef Teal SSC Veteran Group: General Forum Members Points: 260 Visits: 100 I was hoping that the following code:declare @end_date as datetimeset @end_date = '2008-03-10 02:00:00.000'SELECT DATEADD(ms,-1,DATEADD(mm, DATEDIFF(m,0,@end_date)+1,0))would give me '2008-03-31 23:59:59.999'but it doesn't, i get '2008-04-01 00:00:00.000'I think this is because datetime is accurate to roughly 3 milliseconds so it rounds to the next day. If I change it to -2 ms....SELECT DATEADD(ms,-2,DATEADD(mm, DATEDIFF(m,0,@end_date)+1,0))I correctly get '2008-03-31 23:59:59.997'So the question is: How do I accurately determine the last day in the month for a given date, to the last millisecond (999)? Lowell SSC-Dedicated Group: General Forum Members Points: 35905 Visits: 40249 I personally use the 997 milliseconds, otherwise it;'s the next day.`SET DATEFIRST 1declare @mon datetime, @fri datetime SELECT @mon =DATEADD(wk, DATEDIFF(wk,0,GETDATE()), 0) , @fri =DATEADD(ms,-2,DATEADD(wk, DATEDIFF(wk,0,GETDATE()), 0)+ 5 ) Results:Monday = 2009-02-16 00:00:00.000 Friday = 2009-02-20 00:00:00.000 EODFri = 2009-02-20 23:59:59.997--so i would use thhoise dates for a BETWEEN command:SELECT...WHERE SOMEDATE between @mon and @fri` Lowell--help us help you! If you post a question, make sure you include a CREATE TABLE... statement and INSERT INTO... statement into that table to give the volunteers here representative data. with your description of the problem, we can provide a tested, verifiable solution to your question! asking the question the right way gets you a tested answer the fastest way possible! Luke L SSCarpal Tunnel Group: General Forum Members Points: 4819 Visits: 6136 A lot of it depends on what you are trying to do. If you are accepting dates without time from your users and or are passing them in yourself, Instead using "columnname between @Start_Date and @EndDate ", You could use columnName >= @Start_Date AND columnName < datetime(d,1,@EndDate) For the month of January you end up with >= '2009-01-01 00:00:00.000 and < '2009-02-01 00:00:00.000'-Luke.Edited to correct things the page stripped out... To help us help you read thisFor better help with performance problems please read this