Try this:
1. Group by Code.
2. Group by Date - Set the group sort Descending so that your most recent date is the first record.
3. Set up a Select filter that will select all data with a date less than or equal to 3/1/2010. If you want, you can create a parameter so that the user can change this date at run time. You then use the parameter in your filter.
3. Put all of your data in the group Code group header section and suppress the Date group header and footer section and the details section.
This will display the data for the most recent entry that is on or prior to your 'As Of' date.
-Dell