Interactive SQL Course

A comprehensive SQL course designed to change the way you think about SQL forever. Together we will walk the path to understand how this language works and gain all the necessary skills to use it effectively at work.

More advanced courses available

Module 0

Introduction

In this short module, we'll take a look at how this course's platform works and learn how to get the most out of it. And also get information about our community.

Course structure

Module 1

Fundamentals

This module is designed to give you a basic understanding of databases and fill in potential gaps. Also in this module, we will get acquainted with the terminology of relational DBMS.

Databases and DBMS

Relational databases

Key-value databases

Document-oriented databases

Structure of relational databases

Introduction to SQL

Module 2

Basis of selection I

In this module we will learn how to write our first SQL queries, deal with such important concepts as conditional selection, sorting and data grouping.

Basic SQL Query Syntax

Duplicate elimination, DISTINCT

Conditional WHERE operator

Operators IS NULL, BETWEEN, IN

Regular expressions

Sorting, ORDER BY operator

Grouping, GROUP BY operator

Aggregate functions

Operator HAVING

Module 3

Basis of selection II

We continue to write increasingly complex select queries: we learn how to get data from several tables, write subqueries, and get acquainted with a common table expression.

Multi-table queries, JOIN operator

Selection limit, operator LIMIT

Subqueries with one row with one column

Subqueries with multiple rows and one column

Multi-column subqueries

Correlated Subqueries

Common Table Expressions, WITH

Combining queries, operator UNION

Conditional logic, CASE statement

Conditional function IF

Module 4

Data manipulation

In the previous modules, we learned how to write select-only queries, it's time to fool around more seriously: we get acquainted with adding, updating, and deleting records.

Adding data, INSERT operator

Updating data, UPDATE operator

Deleteing data, DELETE operator

Module 5

Advanced SQL

Let's start learning more advanced SQL topics and delve into the ones we've already covered.

Working with data types

Numeric data type

Type conversion functions

Window functions

Partitions in window functions

Sorting within a window

Window frames in window functions

Types of window functions

Locking in DBMS

Creating transactions

Stored procedures and functions

Stored functions

Stored procedures

Operators IF, CASE, WHILE in stored procedures

Event scheduler

Module 6

Databases and tables

It's time to work not only with ready-made databases, but also learn how to create your own.

Creating and deleting databases

Creating and deleting tables

Data types for table columns

String data type

Numeric data type

VIEW Statements

ready to level up?

For those already fluent in SQL

Once the free course clicks, you write SQL with confidence. Where to go next is up to you — some head into performance, others into analytics, others into data architecture. We have an advanced course for each track — deep dives on real-world tasks.

SQL Query Optimization in PostgreSQL

Premium

PostgreSQL

10 hours

Stop guessing why your queries are slow. Learn to read EXPLAIN, pick indexes for specific tasks, and speed up queries by 100x+ on real production cases.

Close 'this query is slow' tickets yourself — via EXPLAIN, indexes, statistics
Cut latency on slow production queries by 10–100×
Explain to your team why the planner picked this plan

SQL for Data Analysis

Premium

MySQL

PostgreSQL

15 hours

Learn to answer product questions right in the database — no dumping into Python or BI tools. You'll master pivot tables, time series analysis, retention, funnels, and user segmentation — all in pure SQL.

Answer product questions in Slack in minutes, not days
Build cohorts, funnels, and retention in pure SQL — no Python exports
Stop hitting the GROUP BY ceiling — windows and time series handle 80% of cases

DB Design and Architecture

Premium

PostgreSQL

15 hours

From the first table to a live system under load. Learn not to memorize answers but to spot the forks: which key, which type, which lock, how to migrate the schema without taking prod down.

Design schemas that won't be rewritten in a year under load
Implement tricky cases — history, hierarchies, JSONB — without code-side hacks
Ship migrations on big tables without 'we'll need a one-hour outage'

SQL for interviews

Premium

MySQL

PostgreSQL

8 hours

A small set of patterns covers most SQL interview tasks. You learn to recognize them by their signal words and pull out a ready-made skeleton — on real tasks from Ozon, VK and Yandex.

You read the statement and see the construct at once, even on an unfamiliar task
You solve in minutes what looks unsolvable without practice
You walk into the interview confident — every pattern already solved ten ways

All courses are included inPremium— along with AI hints, certificates, and everything else.