271. How to generate number or date sequences

In this lesson, we’ll figure out how to generate a sequence of numbers or dates. In the course, we saw how handy it is to have such a helper table: if in some query we aggregate by date, for example, we might see a result like this:

date number_of_purchases
2020-01-01 12
2020-01-04 8
2020-01-12 9

What we really want, especially when plotting this data, is to have no missing dates in the output:

date number_of_purchases
2020-01-01 12
2020-01-02 0
2020-01-03 0
2020-01-04 8
2020-01-05 0

If we only have a table with a date...

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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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