Synopsis: Ambiguous Groups
Let's learn how using ambiguous groups causes an antipattern.
We'll cover the following...
Suppose that your boss needs to know which projects in the bugs database are still active and which projects have been abandoned. One report they ask you to generate is the latest bug reported per product. You write a query using the MySQL database to calculate the greatest value in the date_reported column per group of bugs sharing a given product_id. The report looks like this:
| product_name | latest | bug_id |
|---|---|---|
| Open RoundFile | 2010-06-01 | 1234 |
| Visual TurboBuilder | 2010-02-16 | 3456 |
| ReConsider | 2010-01-01 | 5678 |
Your boss is detail-oriented, and they spend some time looking up each bug listed in the report. They notice that the row listed ...