Can you help me with this query?

I have this lab and I really have no idea where to start. I read the chapter in-depth over 2 times and still am quite clueless...

The short version of the task at hand:

Determine which books generate less than 55% profit and how many copies of those books were sold.

I am working with (what tables I think i'll need to incorporate) two tables and the structures are as follows:

BOOKS table
isbn
title
cost
retail

ORDERITEMS table
order#
item#
isbn
quantity

I know to get profit is AVG(retail-cost) and I know what NEEDS to be done (JOIN using the isbn column), just can't figure out the syntax.

Help/hints would be greatly appreciated

for simple join try this syntax and replace your actual field name

Yes I understand the syntax of the join, just to limit the results of the books that are below 55% of the profit is what is confusing me.

Something like

HAVING AVG(retail-cost) < .55

This is what I don't understand - the rest of the problems of the lab were easy.

I think you need something like this:



You do not need the AVG function.
Cost and retail are in the BOOKS table not the ORDERITEMS table so the relationship is constant
(at least as per your information)

Clive

clivew, thank you muchly for your reply. Can you please explain to me how you came up with 1.55?

A profit of 55% requires a selling price of 1.55 * Cost Price.

Cost + 55/100*Cost = Cost * 1.55

Clive

Thank you soooooo much clivew! That cleared everything right up for me. My head-ache may now start to dull and settle down...

Thanks man for explaining all of that to me.