Quiz
Check your understanding
Short self-assessments, not graded exams. You get a score at the end rather than an answer key — so you can see which parts are worth re-reading.
Nothing matches. Try different words, or pick All topics.
0 to Hero SQL — Stage 1: Foundations
The first three lessons: the relational model, SELECT and its clauses, NULL and three-valued logic, and grouping without double counting. PostgreSQL and MySQL both appear.
0 to Hero SQL — Stage 2: Joins and shaping
Joins and the conditions that quietly change them, subqueries and CTEs, set operations, and window functions — including the default frame that catches almost everybody once.
0 to Hero SQL — Stage 3: Design and production
Constraints and types, indexes and query plans, isolation levels and locking, and the patterns a live database needs — upserts, keyset pagination, batched deletes and online migrations.
AI-Assisted Engineering
Working with coding agents deliberately — spec before code, skills vs agents, MCP, context and token discipline, and reviewing output that is plausible rather than correct.
Architecture Trade-offs
The decisions that come up in real design reviews — event-driven vs request-response, CQRS, service boundaries, sagas, idempotency, and the arithmetic of synchronous chains.
Git Basics
Working with Git without fear — the staging area, branches, what merge conflicts really are, and which commands rewrite history.
HTTP & REST Basics
How the web actually talks — methods and what they promise, the status codes that matter, headers, and the REST conventions worth following.
Java Fundamentals
The Java basics that trip people up early — == versus equals, immutable Strings, autoboxing, collections, inheritance and exceptions.
Modern Java in Practice
Records, sealed types, virtual threads, structured concurrency, streams and the equals/hashCode contract — the parts that change how you write Java, and the edges where they bite.
Payments & PCI DSS
Card payment mechanics and the rules around cardholder data — auth vs capture, void vs refund, 3DS liability, reconciliation, tokenisation and PCI scope.
Spring Boot Basics
Your first Spring Boot service — beans and injection, the stereotype annotations, mapping a request, and where configuration comes from.
Spring Boot in Practice
The Spring Boot behaviour that actually bites in production — proxies, transactions, JPA fetching, config precedence, and test slices.
SQL Basics
Reading and writing everyday SQL — joins, NULL handling, grouping, and the statements you should be nervous about running without a WHERE.
SQL, Indexes & JPA
The database layer where performance is actually won or lost — isolation levels, index eligibility, pagination, JPA fetching and locking, and migrations that do not lock a live table.
Surviving Production
The wiring that decides whether a service degrades or falls over — circuit breakers, retries and backoff, bulkheads, timeouts, probes, SLOs and the observability that makes an incident diagnosable.
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