To calculate ROI for a specific marketing campaign we need to know 2 numbers:
- total spend. We’d need to apply grouping and summing in marketing_spends table
- total earnings. We’d need to look at users who were attributed to this campaign and calculate the sum of their purchases. Wow, that’s even more tricky – users and purchases are 2 different tables
The solution to this problem and many more data problems is joining two or more tables.
Joining tables is basically forming a new table which is the combination of two or more tables. Once...
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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.