SQL & Databases

Every backend eventually comes down to a database, and most performance problems, data bugs, and 3am pages trace back to SQL someone didn't fully understand — a missing index, an N+1 query, a join that should've been a subquery. SQL isn't just CRUD syntax; it's a declarative language for describing exactly the data you want, and the database engine's job is figuring out how to get it to you efficiently, if you write it in a way that lets it.

This course teaches you SQL and relational database design the way they're actually used in production — not just SELECT/INSERT/UPDATE/DELETE, but schema design, indexing strategy, query optimization, and transactions that keep your data consistent under concurrent load. You'll go from basic queries to reading query plans and understanding why one query is fast and an equivalent one is slow.

Every module ends with a hands-on project. You'll query and join real relational data, design and normalize a schema from scratch, and optimize a set of slow queries using indexes and query plan analysis. By the end of the course, you'll be able to design a proper schema, write efficient queries, and reason about performance instead of guessing at it.