The following sections cover some common business questions and how they can be solved by using queries. You can adapt the queries to cover various questions common to developers. Some business questions answered are as follows:
How many times do I have to rent a tape before it pays for itself? The section “Grouping to Get Percentages” shows how to get the percentage of a rental cost to retail cost of a tape, thus allowing you to use it to get the number of times you need to rent it out.
In some cases, duplicate records slip in and need to be taken care of. The section “Finding and Deleting Duplicate Records” shows how to perform this task.
Sometimes it takes a few levels of queries to get to the desired results when ...