150. Introduction to window functions

In this lesson we’ll look at the alternative approach to solve the problem from the previous lesson. Namely, select the very first account for each user.

Imagine, if accounts table would have an index for each account per user. That way we’d just select all accounts where index equals to 1.

Turns out SQL has a special functionality for such calculation. It’s called window functions.

We’ve already met two type of functions.

Scalar functions

Scalar functions accept one or more values as an input and return one or more values as an output. For...

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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
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