beginner

Introduction to SQL

Build a strong foundation in SQL for data analysis. Progress from understanding database schemas and writing basic SELECT queries to mastering joins, aggregates, data manipulation, and safe table design—preparing you for real-world data analyst tasks.

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1,212 learners

Verified skills you'll gain

INTERMEDIATE

Data Cleaning and Preprocessing

INTERMEDIATE

Data Querying and Retrieval

Tools you'll use

PostgreSQL

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Course 2

Keys, Relationships & Joining Data

10 lessons

Move from single-table work to relational thinking. Learn how keys define relationships and how JOINs combine tables, supported by more advanced filtering tools.

Course 3

Aggregation, Grouping & Subqueries

9 lessons

Summarize data, filter aggregated results, nest queries, and peek inside how the SQL engine processes statements—all through code illustrations.

Course 4

Data Manipulation & Transaction Control

10 lessons

Modify data safely while enforcing rules that preserve accuracy. Wrap changes in transactions so mistakes remain reversible—shown via annotated code blocks.

Course 5

Table Creation & Integrity Constraints

10 lessons

Move from manipulating data to defining the structures that hold it. Learners create tables, then layer on constraints that guarantee accuracy, uniqueness, and valid relationships.

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From our community

Hear what our customers have to say about CodeSignal Learn

I'm impressed by the quality and can't stop recommending it. It's also a lot of fun!

Francisco Aguilar Meléndez

Data Scientist

+11

I love that it's personalized. When I'm stuck, I don't have to hope my Google searches come out successful. The AI mentor Cosmo knows exactly what I need.

Faith Yim

Software Engineer

+14

It's an amazing product and exceeded my expectations, helping me prepare for my job interviews. Hands-on learning requires you to actually know what you are doing.

Alex Bush

Full Stack Engineer

I'm really impressed by the AI tutor Cosmo's feedback about my code. It's honestly kind of insane to me that it's so targeted and specific.

Abbey Helterbran

Tech consultant

I tried Leetcode but it was too disorganized. CodeSignal covers all the topics I'm interested in and is way more structured.

Jonathan Miller

Senior Machine Learning Engineer

+12

I'm impressed by the quality and can't stop recommending it. It's also a lot of fun!

Francisco Aguilar Meléndez

Data Scientist

+11