Do You Really Understand SQL’s GROUP BY and HAVING clauses?

There are some things in SQL that we simply take for granted without thinking about them properly. One of these things are the GROUP BY and the less popular HAVING clauses. Let's look at a simple example. For this example, we'll reiterate the example database we've seen in this previous article about the awesome LEAD(), … Continue reading Do You Really Understand SQL’s GROUP BY and HAVING clauses?