Introduction to SQL
Learn SQL from the ground up: queries, database design, indexing, joins, subqueries, and stored procedures. Perfect for beginners entering backend or data engineering.
Oleksii Anzhiiak
Software Architect, Senior .NET Engineer & Co-Founder
By the end you'll be able to
- Write efficient SQL queries for real applications
- Design normalized relational database schemas
- Work confidently with multi-table datasets
- Optimize queries using indexes
- Ensure data consistency with transactions
Is this course for you?
This is right for you if you…
- You're aiming for backend, data-analytics, or any role that touches a database — which is most of them
- You write code that calls an API and the data 'just appears', and you suspect that's a problem
- You took the C# foundation course and the next obvious gap is 'how do I actually store stuff'
Don't take this course if you…
- You only want to learn NoSQL — there's a separate MongoDB course (#9). SQL is still the ground truth, but if you're 100% sure your stack will be document-store-only, skip ahead
- You think SQL is 'just SELECT statements' — this course also covers schema design, indexes, and transactions, which is where actual jobs live
- You expect to memorise queries instead of understanding them — query optimisation is reasoning, not recall
Who teaches this
Oleksii Anzhiiak
Software Architect, Senior .NET Engineer & Co-Founder
Oleksii Anzhiiak is a Software Architect, Senior .NET Engineer, and Co-Founder of ToyCRM.com and ProfectusLab. With over 15 years of experience, he specializes in distributed systems, cloud infrastructure, high-load backend development, and identity platforms. Oleksii designs complex architectures, builds secure authentication systems, and develops modern engineering education programs that help students achieve real career results.
Currently leads architecture for ToyCRM.com — a multi-tenant CRM platform built on .NET by our team. The same patterns and design decisions used there appear directly in the courses: identity & auth, distributed services, code review culture. You learn from engineers actively shipping production code, not from a textbook.
Syllabus
This course covers the fundamental SQL concepts and practical skills needed to work with databases:
- 1 Module 1: Introduction to SQL
- 2 Module 2: T-SQL & Writing Queries
- 3 Module 3: DDL Basics
- 4 Module 4: Database Design Fundamentals
- 5 Module 5: JOINs
- 6 Module 6: Subqueries
- 7 Module 7: Indexes
- 8 Module 8: Stored Procedures & User-defined Functions
- 9 Module 9: Transactions
Prerequisites
Basic computer skills and willingness to learn. Course materials will guide you step by step.
No prior SQL experience required. Basic computer and logical thinking skills are enough.
What you'll build
You leave with a personal database (one you designed and seeded yourself) plus a folder of 30+ queries that solve real problems — including the JOIN, the GROUP BY, and the WHERE-EXISTS variants every backend interview tests. SQL is the one skill that travels across every backend stack; learn it once, use it for the rest of your career.
- SQL SELECT queries with filtering and sorting
- JOIN operations across multiple tables
- Aggregations and GROUP BY clauses
- Subqueries and nested queries
- Database normalization principles
- Indexes and query performance basics
- Transactions and data consistency
Where this fits in your career
Read alongside this course
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First lesson on us. Decide after meeting your instructor.
Sit in on the first session. If after lesson 1 you decide the instructor isn't the right fit, you don't pay for it — and no awkward conversation. (Trial offer applies to courses with more than 5 lessons; this one qualifies.)
Pricing & what's included
What's included
- 9 live sessions × 2 hours each — taught by the instructor, not a recording playback
- Slide deck for every session — yours to keep and refer back to
- Working code files and any data files used in class — cloned to your machine
- Weekly homework with personal code review from the instructor
- Recording on request — give the teacher a heads-up ("can't make Tuesday, please record it") and the session is recorded for you
Frequently asked questions
How much time per week will this take?
Plan for the live sessions plus roughly 1.5–2 hours of practice per session. Most students who finish on schedule put in 4–6 hours a week total. If you put in less, you still finish — it just takes longer.
What if I miss a class?
Tell the teacher BEFORE the session — "I can't make Tuesday, please record it" — and the teacher records that lesson and sends it to you. Recordings aren't a default catch-up archive; they're produced on request when you give a heads-up. After the lesson you do the homework, bring questions to the next session.
What's included in the price?
Live sessions with the teacher; the slide deck for each session (yours to keep); the working code files and any data files used in class; weekly homework with code review; and recordings of the sessions you give advance notice for. Anything beyond that — a certificate, alumni access, mock interviews — is listed explicitly in "What's included" above the FAQ for the courses where it applies.
What if I sign up and the teacher isn't a fit?
For courses with more than 5 lessons, the first session is effectively a trial — if after lesson 1 you decide the teacher isn't a fit, you don't pay for it. We'd rather you walk away after one lesson than push through 9 weeks of bad chemistry. (Courses with 5 or fewer lessons are short enough that the standard pricing applies — the trial offer doesn't make sense at that length.)
Can I get a refund partway through?
Yes, while more than half the course is still unused — i.e. you've attended fewer than 50% of the lessons. The refund covers the unused portion proportionally. Past the halfway point we don't refund, on the assumption that the value has been delivered.
Can I switch the language of instruction?
The live sessions run in the language listed under "Available Languages" above. Slides and code files are typically available in all four (English, Russian, Ukrainian, Georgian). Many students attend sessions in one language and read materials in another — that's normal.
Will I be ready for a real job after this course?
One course rarely gets anyone hired by itself — for any field. What this course gives you is the foundation a junior hiring manager expects: working code you wrote yourself, the vocabulary to read other people's code, and the practice habits that make you employable. The honest answer to "am I ready?" is on our roadmap (link in the page header) — open the level you want to reach and read the "You're ready when" checklist.
Can I pay in instalments?
Yes for courses with a "Monthly Payment" option in the at-a-glance ribbon — usually two or three equal monthly payments. Courses without that option are paid in one go. If the price is the blocker, write to us — we look at every case.