In the select query window you can choose to return a particular number of queries which you can set to one. You can also order your returns by the bid value and so cause that one to be the one returned.
However; There are two (soluble) problems you will encounter.
1) The choose only one...
I have an example question from an old exam. You make a database where users bid for house designs and if they are successful in their bid they knock out the lowest bidder for that design of house.
When the bidding is over there are 57 successful bids and 57 plots. The successful bids are...