Shoutbox

Okay, well i have this project I'm doing and i need some guidance.

Basically, i have to create 2 queries, and I'm not quite sure how to do it.

I have tables that contain information about

a) the sales people (address, suburbs they work in, name, surname etc)
b) the customers (name, surname, address, product purchased, sales person)
c) the products (product name, price and details about the product)

Basically, i have to link these tables in the query to

a) find how many sales each sales person has made and sort them by the suburb in which they're sold in and;
b) Find out which products are being sold more than others

Basically, i don't know how to link the queries together to create this information. I'm not looking for a direct answer, but guidance and tips on how to figure it out - or maybe even an example of something similar to this, as i wish to be able to do more of these in future.

Thanks in advance.