Launch Special -- Get 40% off for a limited time. Price increases soon.
For Data Engineers, Analysts & Developers

Stop Failing SQL Interviews
You Should Be Passing

The complete 17-book system that transforms "I know SQL" into "I just got the offer" -- even if you have been rejected before.

Join data professionals who cracked interviews at top tech companies

Yes, I Want to Crack SQL Interviews

Instant download - Start studying in 2 minutes

✅ Lifetime Access Guaranteed

These patterns appear in interviews at

Google Meta Amazon Microsoft Apple Netflix

Let Me Guess... This Sounds Familiar

You are good at your job. You write SQL every day. But when you walk into that interview room, something changes.

😤

You "Know" SQL -- But Still Fail

You have been writing queries for years. But interview questions feel like a different language. The syntax is the same, but you cannot connect the dots under pressure.

Another rejection email. Another month of job searching.
🎲

LeetCode Feels Like Gambling

You grind problems randomly. Some days you feel smart. Other days, you stare at "Medium" problems for an hour with nothing. No system. No progress you can measure.

100 hours of practice with nothing to show for it.
😰

Your Mind Goes Blank

You have solved this exact type of problem before. But with the interviewer watching, the clock ticking, your brain freezes. You know you are better than this.

Walking out knowing you could have done better.

Here is What This Is Really Costing You

$30,000 - $80,000

That is the salary difference between your current role and the job you keep missing. Every month you wait is another month of leaving money on the table -- while someone else takes your spot.

There is a Better Way

What if you could walk into any SQL interview knowing exactly what patterns they will test -- and exactly how to solve them?

CS

Hi, I am Coskan

I have spent 15+ years in data architecture and BI at retail, fintech, and e-commerce companies. I have sat on both sides of the interview table hundreds of times.

I built this system because I got tired of watching talented people fail interviews they should have passed.
17
Complete Books
135
Chapters
134
Pattern Cards
6
Week System

The Transformation

Before

  • Freeze when you see a new problem
  • Random LeetCode grinding
  • Cannot explain your thought process
  • Panic when time runs out
  • Forget patterns you have learned
  • Reject - Doubt - Repeat
→

After

  • Instantly recognize pattern types
  • Structured 6-week study system
  • Clear framework to talk through solutions
  • Confident time management
  • 134 pattern cards for quick recall
  • Interview - Offer - Negotiate

What is Inside the System

17 books covering every SQL pattern that appears in technical interviews

B00

Foundations & Mental Models

How to think about SQL before writing queries

B01

Single-Table Wins

Master the basics that trip up most candidates

B02

Relationships & JOINs

JOINs, EXISTS, anti-joins, and when to use each

B03

Set Operations

UNION, INTERSECT, EXCEPT patterns

B04

Aggregation Mastery

GROUP BY edge cases and advanced aggregations

B05

Subquery Patterns

Correlated, scalar, and derived table mastery

B06

Window Functions I

ROW_NUMBER, RANK, DENSE_RANK, NTILE

B07

Window Functions II

LAG, LEAD, running totals, moving averages

B08

Time Series SQL

Date math, periods, and temporal queries

B09

Gaps & Islands

The classic interview pattern, demystified

B10

Strings & Regex

Text manipulation and pattern matching

B11

Reshaping Outputs

PIVOT, UNPIVOT, and result formatting

B12

Recursion & Hierarchies

CTEs and tree traversal patterns

B13

Advanced Patterns

Complex real-world query patterns

B14

DML Track

INSERT, UPDATE, DELETE for interviews

B15

Query Optimization

Performance tuning and execution plans

B16

Problem-Solving Mastery

How to approach any SQL problem systematically

134 Pattern Cards -- Your Interview Cheat Code

See a problem. Recognize the pattern. Apply the template. Solve in minutes. These cards make pattern recognition automatic.

NULL Handling Self-Joins Running Totals Gaps & Islands Top-N Per Group Date Spines Sessionization Funnel Analysis Deduplication Pivot Tables Recursive CTEs Anti-Joins Window Frames Consecutive Days Moving Averages Cumulative Sums Percentile Ranks + 117 more

What Data Professionals Are Saying

*****

"Finally, someone explains the WHY behind SQL patterns, not just the syntax. After 3 failed interviews, I used this system for 4 weeks and landed a Senior Data Engineer role."

AK
A.K.
Senior Data Engineer
*****

"The pattern cards are genius. I keep them open during practice. Now when I see a problem, I immediately know which pattern to apply. Game changer for window function questions."

MR
M.R.
Data Analyst to Data Engineer
*****

"I have bought SQL courses before. They teach syntax. This teaches thinking. The Gaps and Islands chapter alone saved me in my Meta interview. Worth 10x the price."

TC
T.C.
Software Engineer

Everything You Are Getting Today

✓
17 Complete PDF Books (500+ pages) Comprehensive coverage of every SQL interview topic. From fundamentals to advanced patterns.
Value: $297
✓
134 Pattern Cards Quick-reference templates. See a problem, match the pattern, apply the solution.
Value: $97
✓
Practice Database (PostgreSQL) Real schema with realistic data. Practice exactly what you learn immediately.
Value: $47
✓
6-Week Study Plan No more "what should I study today?" Follow the system, track your progress.
Value: $47
✓
Lifetime Access + Future Updates Buy once, own forever. Any new content added is yours automatically.
Value: Priceless

Get Instant Access

One payment. Lifetime access. No subscriptions.

LAUNCH SPECIAL -- 40% OFF
Total Value: $488
$49 USD
One-time payment - Instant download
  • 17 Complete PDF Books
  • 134 Pattern Cards
  • Practice Database
  • 6-Week Study Plan
  • Lifetime Access
  • Future Updates Included
Get Instant Access
✅ Secure checkout via Gumroad

Still Have Questions?

"I can find SQL tutorials for free online"
You can. But free tutorials teach syntax, not patterns. They do not show you how problems connect or how to think under interview pressure. This system does.
"I do not have time to study"
The 6-week plan is designed for 1-2 hours per day. That is less time than random LeetCode grinding -- with better results.
"What if I am not advanced enough?"
If you know basic SQL (SELECT, JOIN, WHERE, GROUP BY), you are ready. The system takes you from there to interview-ready.
"$49 is expensive"
One successful interview could mean $30K-$80K more per year. If this helps you land even one better offer, the ROI is 600x-1600x.

Frequently Asked Questions

What format are the books in?
All 17 books are delivered as PDF files that work on any device. You also get the practice database as a SQL file and pattern cards as a CSV for easy reference.
What SQL dialect do you cover?
The primary dialect is PostgreSQL, which is the most common in interviews. Where syntax differs, we note MySQL and SQL Server alternatives. The patterns themselves are universal.
How is this different from LeetCode?
LeetCode gives you problems. This teaches you patterns. When you understand the underlying pattern, you can solve any problem that uses it -- even ones you have never seen before.
How quickly can I see results?
Most people notice a difference after the first week. By week 3, you will recognize patterns automatically. The full 6-week system prepares you for any SQL interview.
Do I get lifetime access?
Yes. Buy once, download forever. Any future updates or new content added to the system is yours automatically at no extra cost.
What if I have questions while studying?
Email support@cracksql.com anytime. I personally answer questions about the material.
Launch pricing will not last forever. Lock in 40% off while you can.

Your Next SQL Interview Does Not Stand a Chance

In 6 weeks, you could be walking into interviews with complete confidence -- knowing exactly what patterns they will test and exactly how to solve them.

Get Instant Access for $49

Join data professionals who stopped guessing and started passing.

The "No Fluff" Promise

This system contains 500+ pages of pure, actionable content. No filler. No fluff. No outdated techniques. If you follow the 6-week plan and do not feel significantly more confident in your SQL interview skills, email me and I will personally help you get unstuck.