Mastering SQL Query For Interviews and Production

Learn SQL from the ground up with PostgreSQL, and 50+ interview questions. Apply this to MySQL, SQL Server etc
What you'll learn

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Explain relational databases, tables, keys, relationships, constraints, and how SQL queries produce results
Write SQL queries to filter, sort, transform, and summarize data while handling NULLs and duplicates correctly
Combine and analyze data using joins, subqueries, CTEs, and window functions in PostgreSQL.
Solve practical SQL problems, verify results, and explain query logic, assumptions, and common mistakes.
Solve 100+ SQL interview problems using joins, subqueries, CTEs, and window functions, and explain your reasoning and edge cases clearly.
Requirements

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Basic computer skills, including installing software and opening files
A computer with PostgreSQL and a query editor such as pgAdmin for hands-on practice
Willingness to pause lessons, try exercises, and experiment with queries
Description

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Build a strong SQL foundation, then apply your knowledge to practical interview problems. This course combines structured lessons on relational databases with 100 SQL interview questions, helping you understand both how queries work and why their results are correct.
Begin with the essentials: databases, tables, rows, columns, keys, relationships, constraints, and data types. Learn how SQL retrieves and transforms data, and develop confidence with SELECT statements, filtering, sorting, expressions, and aggregate functions. Understand how NULL values and duplicates affect your results so you can avoid common mistakes early.
As you progress, explore joins, subqueries, common table expressions, recursive queries, and window functions. Work through examples involving rankings, running totals, moving averages, date calculations, and customer activity. You will also encounter transactions, parameterized queries, and practical ways to investigate query performance.
The lessons use PostgreSQL and small datasets that make each operation easier to follow. Rather than simply copying a finished query, you will predict the output, trace the logic, compare the result, and attempt a practice variation. Supplied SQL files and expected outputs support your independent practice.
The interview section gives you 100 opportunities to apply these concepts. Practice breaking down a question, identifying what each output row should represent, choosing a suitable SQL approach, and checking boundary cases. Learn to explain your assumptions and recognize why a plausible query might return the wrong answer.
This course is suitable for beginners, aspiring data analysts, developers, students, and professionals preparing for SQL interviews. No previous database experience is required for the foundations section. Learners with basic SQL knowledge can use the interview section to strengthen their problem-solving skills.
Bring a computer with PostgreSQL and a query editor, along with a willingness to pause, experiment, and practice. By the end, you will have a structured approach to writing SQL, validating results, and explaining your reasoning clearly.
Who this course is for

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Beginner to Intermediate developers including database engineers who need to understand concpets and solve tricky interview questions.
Homepage

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