Integer to date in SQL Server 2005

Question

I need to create a loop to pull records that are within a quarter from 2006 to the present.  I have created a routine to increment the months and years using integers to get the begin and end dates for each quarter.  I can't seem to use the integers
to create a date.
DECLARE @EarnYear int,
@Beginer int,
@First int,
@QtrBegin datetime
SET @EarnYear = 2006
SET @Beginer = 1
SET @First 1
SELECT (CAST(CAST(@EarnYear as char(4)) +
right('00' + cast(@Beginer as varchar(2)),2) +
right('00' + cast(@First as varchar(2)),2) as datetime) as @QtrBegin
Can anyone help?  Thanks.

Answer 1

You don't want to do it as integers.  When you put an integer into a datetime you get the date that is that many days since Jan 1, 1900.  Sso if you convert the integer 20060101 to a datetime, you are trying to get the date that is 20,060,101 days
pass 1/1/1900 which would be a date in the year 54921.  But the largest possible datetime value is Dec 31, 9999, so you get an error.
You can do it the way you are doing it - that is build a character value containing '20060101' and converting it to a date.  But the best way to do this sort of problem (and many others dealing with dates) is to build a calendar table.  For information
on how to build a calendar table and some of the many uses for a calendar table, see
http://sqlserver2000.databases.aspfaq.com/why-should-i-consider-using-an-auxiliary-calendar-table.html.  (Note that this webpage was written for an older version of SQL Server.  If you are on SQL 2008 or later, you probably want to make the datatype
of the dt column date instead of smalldatetime.)
Once you have this table getting the beginning and ending date of every quarter from 2006 to the present is just
Select Y As [Year], Q As Quarter, Min(dt) As QuarterStart, Max(dt) As QuarterEnd
From dbo.Calendar
Where Y >= 2006 And dt <= GetDate()
Group By Y, Q
Order By Y, Q;
Tom