Discover curated SQL courses and learning paths from our community
Build a fully functional budget tracking system in SQL, from scratch. Each article adds to a working schema based on double-entry bookkeeping, the same system that has powered financial record-keeping since the 1400s. You'll design accounts, record balanced transactions, enforce integrity with triggers, and generate real financial reports. No toy examples. Every table, constraint, and query is something you could use in production.
A series on PostgreSQL indexing, how indexes work, when to use them, and how to prove it with EXPLAIN ANALYZE. Starts with single-column basics and builds through composite indexes, covering indexes, and beyond.
Practice SQL interview questions commonly asked at tech companies. Each book presents a real-world scenario, explains the underlying SQL pattern being tested, and provides a dataset to write your solution against. Topics covered include self-joins, window functions, gaps and islands, time-series comparisons, and aggregate filtering. Suitable for anyone preparing for data engineering, analytics, or backend engineering interviews where SQL proficiency is evaluated.
Learn to write clearer, more maintainable SQL queries with Common Table Expressions (CTEs). This collection shows practical examples of using CTEs to break down complex queries into logical steps, from simple filtering and aggregation to advanced patterns like recursive queries and gaps-and-islands problems. Each example includes working code you can run immediately in PostgreSQL, MySQL, Oracle, or MariaDB—no signup required. Whether you're analyzing time-series data, building hierarchical reports, or optimizing query performance, CTEs are an essential SQL skill.
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