Counting unique values in a found set

[pennsy]

I have a feeling that this question is answered all over the forum, but I can't find the right way to phrase my search query. If someone could just shoot me a link to the right answer, I would be grateful.

I have a file of data from hand written work logs with the following pertinent fields.

Date

Name

Hours worked

A single person will have several entries per day, one for each project they worked on.

JB 2hrs

TR 1hr

JM 2hrs

TR 6hrs

JB 4hrs

JM 2hrs

JM 2hrs

etc...

I want to be able to count how many different people were at work, (ie, how many unique names) in a time period.(records in a range of dates)

I have written the summary report, but need the number of unique names to calculate the total worker-hours in the found time period. (unique names x 8hrs x number of days)

Thanks,

Pennsy