connecting three tables with left join and ordinary join

[sixtus]

I need a little help.
I have 3 Mysql tables:
Week (with columns day and hour)
Activity (with columns day, hour, activityid and ac_text)
Person (with columns name and activityid)

I would like to create a scheme showing the activities during a week sorted on days and hours. If I ignore the person table I can fix it with the statement:
Select …. From week left join activity on (week.day = activity.day) and (week.hour = activity.hour) order by day, hour
I can then make a loop (I am usin asp.net) that writes the activities.
My problem is when I try to combine the persons to the activtities in an given hour (there is at least one person connected to each activity). How do I do that ? (activity.activityid = person.activityid).

I have a little extra question. When I make the join above and print the result (day, time and activity) there isn’t any output if no activity matches a given day and hour. How do I do when I always want to print day and hour and add activity where such exist.

I hope I can get some help.