Question

I am trying to correct the sort order of my ASP.NET drop down list.

The problem I have is that I need to select a distinct Serial number and have these numbers organised by DateTime Desc.

However I cannot ORDER BY DateTime if using DISTINCT without selecting the DateTime field in my query.

However if I select DateTime this selects every data value associated with a single Serial number and results in duplications.

The purpose of my page is to display data for ALL Serials, or data associated to one serial. When a new cycle begins (because it is a new production run) the Serial reverts to 1. So I cannot simply organise by serial number either.

When I use the following SQL statement the list box is in the order I require but after a period of time (usually a few hours) the order changes and appears to have no organised structure.

alt text http://img7.imageshack.us/i/captureky.jpg/

I’m fairly new to ASP.NET / SQL, does anyone know of a solution to my problem.

Answer 1

If you have multiple date times for each serial number, then which do you want to use for ordering? If the most recent, try this:

SELECT  SerialNumber,
        MAX(DateTimeField)
FROM    Table
GROUP BY SerialNumber
ORDER BY 2 DESC