Premium
Log in
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.
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.
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
Database types
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
Literals
Function usage
Duplicate elimination, DISTINCT
Conditional WHERE operator
Operators IS NULL, BETWEEN, IN
Operator LIKE
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
INNER JOIN
OUTER JOIN
Selection limit, operator LIMIT
Subqueries
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.
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
Date and time
Type conversion functions
Window functions
Partitions in window functions
Sorting within a window
Window frames in window functions
Types of window functions
Transactions
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.
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.
- Figure out why your index isn't being used
- Read EXPLAIN ANALYZE and find the bottleneck
- Rewrite queries to fit your SLA
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.
- Calculate retention in a single query
- Build an event-based funnel
- Master windows and time series