One of the account managers at work asked me if I could give her a summary of how many support requests are opened and closed each day.

Update 23 Jan 2011

Thanks to nedoboi for pointing out a bug with my code in the comments, and posting a fix!

Here’s a simplified version of our HelpRequest table.

CREATE TABLE [dbo].[HelpRequest](
	[Id] [int] IDENTITY(1,1) NOT NULL,
	[CreatedTimestamp] [datetime] NOT NULL,
	[ClosedTimestamp] [datetime] NULL
) ON [PRIMARY]

Each HelpRequest has a CreatedTimestamp and a ClosedTimestamp which are both datetimes. One way to get the Date part of a datetime is like so:

SELECT CAST( FLOOR( CAST( CreatedTimestamp AS float) ) AS smalldatetime) AS OpenedDate

Let’s put that in a function.

CREATE FUNCTION truncateDate ( @date datetime )
RETURNS datetime
AS
BEGIN 
    RETURN CAST( FLOOR( CAST( @date AS float) ) AS smalldatetime)
END

Now let’s do a GROUP BY to get all the HelpRequests opened on a given date range:

SELECT dbo.truncateDate(CreatedTimestamp) AS Report_Date,
COUNT(1) AS Qty_Opened
FROM HelpRequest
WHERE CreatedTimestamp BETWEEN '2010-01-01' AND '2011-01-13'
GROUP BY dbo.truncateDate(CreatedTimestamp)

We can do the same thing, but for closed help requests. No need to show that code.

Finally, do a join union to get the Open and the Closed for each day.

SELECT Report_Date, SUM(QTY_OPENED) AS Opened, SUM(QTY_CLOSED) AS Closed
FROM
(
	SELECT
	dbo.truncateDate(CreatedTimestamp) AS Report_Date,
	COUNT(1) AS Qty_Opened,
	0 AS QTY_CLOSED
	FROM HelpRequest
	WHERE CreatedTimestamp BETWEEN '2010-01-01' AND '2011-01-13'
	GROUP BY dbo.truncateDate(CreatedTimestamp)
UNION
	SELECT
	dbo.truncateDate(ClosedTimestamp) AS Report_Date,
	0 AS QTY_OPENED,
	COUNT(1) AS QTY_CLOSED
	FROM HelpRequest
	WHERE ClosedTimestamp BETWEEN '2010-01-01' AND '2011-01-13'
	GROUP BY dbo.truncateDate(CLOSEDTIMESTAMP)
) DATES
GROUP BY Report_Date
ORDER BY Report_Date

Mega-ugly, but it works. Too bad I don’t have a DBA to help me tidy it up! Feel free to write a comment with any suggestions.
Thanks again to nedoboi for the bug fix.

OK, final task is to parameterize the above query and then add it to SQL Server Reporting Services. A little bit of playing and, voila;