0 - 2 of 2 tags for distinct count

Hi,

Need help on the following scenario.

Consider the following dataset

transaction created_date closed_date

1                1-jan-2011       5-jan-2011

2                2-jan-2011       10-jan-2011

3                5-jan-2011       5-feb-2011

4                10-jan-2011     6-mar-2011

I need to do a conditional count on a number of assessments. It needs to be a distinct count over person and date. My raw data looks something like this:

Name Date Assessment Type Assessment Time
Chuck Smith 6/7/2010 1 6/7/10 1:00
Chuck Smith 6/7/2010 2 6/7/10 1:00
Chuck Smith 6/7/2010 3 6/7/10 1:00
Chuck Smith 6/8/2010 1 6/8/10 1:00
Chuck Smith 6/8/2010 1 6/8/10 2:00
Chuck Smith 6/8/2010 1 6/8/10 3:00
Chuck Smith 6/8/2010 2 6/8/10 1:00
Chuck Smith 6/8/2010 2 6/8/10 2:00
Chuck Smith 6/9/2010 2 6/9/10 3:00
Chuck Smith 6/9/2010 3 6/9/10 14:00