Add A Column If Product Is In Discrepancies Table (was Sql Query)

I have a transaction table (which contains details of all products on all orders)
and is have a discrepancies table which includes details on products that couldnt been found (hence error in stock count)...

Now I want to write a query returning details of all products from a specfic orders.. pretty simple

SELECT product, description, qty
from TRANSACTIONS
where order_no = 'xxx'

but i also want to add an extra boolean column (true if product is in discrepancies table and false if product is not in discrepancies table...will become checkbox at front end)... im not sure how to write this bit....

I know it would a transaction table LEFT JOIN to discrepancies table, but I do not know how to write syntax to add extra column...

Be garteful for any help :confused:

Thanks