In the last lessons we learned
GROUP BY statement. It is the foundation of data analysis with SQL. It allows us to group records and calculate aggregated values on them. Examples are numerous:
- signups by country
- signups by day
- min/max/average age of users
- min/max/average revenue per user/per county/per day etc
The real power comes when we start combining groups and look at our data from different angles. We’ll come to it in one of the next lessons.
You see how powerful
GROUP BY is, this is why it’s important to get it right. Let’s recap the...