112. Setting default values with COALESCE

In the previous exercise about calculating CPA per marketing campaign you might have noticed that not all campaigns have users. There’s no surprise – some campaigns are just experiments and not always bring us users.

That’s what we’re trying to do here – learn everything about data and SQL so we can easily identify such campaigns and shut them down. It’s important not to miss those campaigns in our reports.

How can we lose a campaign in report

Let’s look at the possible query that calculates CPA per campaign:

WITH spend_per_campaign AS ( SELECT...
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Anatoli Makarevich, author of SQL Habit About SQL Habit

Hi, it’s Anatoli, the author of SQL Habit. 👋

SQL Habit is a course (or, as some of the students say, “business simulator”). It’s based on a story of a fictional startup called Bindle. You’ll play a role of their Data Analyst 📊 and solve real-life challenges from Business, Marketing, and Product Management.

SQL Habit course is made of bite-sized lessons (you’re looking at one atm) and exercises. They always have a real-life setting and detailed explanations. You can immediately apply everything you’ve learned at work. 🚀

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-- Type your query here, for example this one -- lists all records from users table: SELECT * FROM users
LIMIT 500
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