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## Window Functions

Interactive Course

Learn how to use analytic SQL functions to deeply understand data.

218

Interactive courses

20 h

Estimated time

164

Users enrolled

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13 ratings

SQL window functions – also known as windowing functions, OVER functions, or analytic functions – are tremendously useful. These functions make building complex aggregations much simpler. In this step-by-step tutorial, we will lead you through SQL window functions. At its end, you'll embrace this topic with ease and feel comfortable using window functions in SQL databases.

Window functions are so powerful that they serve as a dividing point in time: people talk about SQL before window functions and SQL after window functions. Because they were introduced into the standard relatively recently, these functions aren't covered in many SQL courses.

Note: Most popular database engines support window functions; MySQL is the only one that does not.

This course covers the syntax and semantics of SQL window functions. It shows how powerful they are, what the typical use cases are, and how to use ORDER BY and PARTITION BY to set up a frame for window functions. You'll also learn the difference between ROWS and RANGE clauses.

This course is intended for intermediate users. We assume the user knows the basics of SQL, including:

- How to select from a single table, including writing complex WHERE conditions
- How to JOIN tables
- How GROUP BY and HAVING work

- A web browser
- Knowledge of basic SQL, including JOINs and GROUP BY clauses

- Compute running totals and running averages
- Build rankings
- Find best and worst performers
- Investigate trends across time
- Calculate contributions to the whole, such as commission percentages

You'll also get a deeper understanding of SQL aggregate functions.

- Beginning database analysts
- Developers who want to keep their knowledge of SQL current
- Students taking classes in relational databases
- Anyone who wants to learn SQL window functions

Trial

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Completed

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Exercises done

Get to know tables

Computations with OVER()

Aggregate functions with OVER()

OVER() and WHERE

Summary

Discover how you can define the function window with PARTITION BY

Exercises done

Introduction

PARTITION BY

Learn how you can rank rows with window functions.

Exercises done

Introduction

Ranking functions

Selecting n-th row

Get to know how to create sophisticated window frames for your window functions.

Exercises done

ROWS

RANGE

Default window frame

Introduction

LEAD and LAG

FIRST_VALUE, LAST_VALUE, NTH_VALUE

Create advanced statistics computed independently for various groups of rows.

Exercises done

Introduction

Quick refresher

PARTITION BY ORDER BY with ranking

PARTITION BY ORDER BY with window frames

PARTITION BY ORDER BY with analytical functions

Do you know when window functions are evaluated in a SQL query? Let's find out.

Exercises done

When window functions are evaluated

Window functions and GROUP BY

Master all the skills you acquired so far in our big practice part.

Exercises done

Introduction

Simple OVER()

PARTITION BY

Ranking functions

Window frame

Analytic functions

ORDER BY PARTITION BY

Order of evaluation

Summary

Test the skills you acquired in the whole course with this final quiz.

Exercises done

Introduction

Final quiz

Summary

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