Question

I’m writing a report in Crystal Reports XI Developer that runs a stored procedure in a SQL Server 2005 database. The record set returns a summary from log table grouped by Day and Hour.

Currently my query looks something like this:

SELECT
    sum(colA) as "Total 1", 
    day(convert(smalldatetime, convert(float, Timestamp) / 1440 - 1)) as "Date",
    datepart(hh, convert(smalldatetime, convert(float, Timestamp) / 1440 - 1)) as "Hour"
    `etc...`
GROUP BY 
    Day, Hour

Ignore the date insanity, I think the system designers were drinking heavily when they worked out how to store their dates.

My problem is this: since there are not always records from each hour of the day, then I end up with gaps, which is understandable, but I’d like Crystal to be able to report on the entire 24 hours regardless of whether there is data or not.

I know I can change this by putting the entire query in a WHILE loop (within the stored procedure) and doing queries on the individual hours, but something inside me says that one query is better than 24.

I’d like to know if there’s a way to have Crystal iterate through the hours of the day as opposed to iterating through the rows in the table as it normally does.

Alternatively, is there a way to format the query so that it includes the empty hour rows without killing my database server?

Answer 1

Here’s how I solved this problem:

1. Create a local table in your SQL-Server. Call it “LU_Hours”.
2. This table will have 1 integer field (called “Hours”) with 24 rows. Of course, the values would be 1 through 24.
3. Right join this onto your existing query.
4. You might need to tweak this to make sure the nulls of empty hours are handled to your satisfaction.