Study guide · 8 topics
SQL Exam Study Guide
Eight topic guides covering everything tested on SQL exams and data interviews. Code examples, exam traps, and tips throughout.
Test your SQL knowledge → Free · No sign-upSQL SELECT Explained — WHERE, ORDER BY, LIMIT & DISTINCT
SELECT is the foundation of SQL. Here's what exams test — filtering, sorting, and the operators that trip people up.
Read guide →02 · 7 min readSQL JOINs Explained — INNER, LEFT, RIGHT, FULL OUTER with Examples
JOINs are the most-tested SQL topic. Here's a clear breakdown of every join type with examples you can run.
Read guide →03 · 5 min readSQL GROUP BY & Aggregates — COUNT, SUM, AVG, HAVING Explained
Aggregation is tested in every SQL interview. Here's what you need to know — GROUP BY, HAVING, and the WHERE vs HAVING trap.
Read guide →04 · 6 min readSQL Subqueries Explained — Correlated, EXISTS, IN with Examples
Subqueries unlock powerful data retrieval patterns. Here's what SQL exams test — correlated vs non-correlated, EXISTS, and IN.
Read guide →05 · 7 min readSQL Window Functions Explained — RANK, ROW_NUMBER, LEAD & LAG (With Practice Quiz)
Window functions are the most powerful — and most-tested — advanced SQL feature. Here's everything you need to know.
Read guide →06 · 5 min readSQL Indexes Explained — Types, When to Use, and Query Performance
Indexes are the key to query performance. Here's what interviews test — types of indexes, when they help, and when they don't.
Read guide →07 · 6 min readSQL Transactions Explained — ACID Properties and Isolation Levels
Transactions ensure data integrity. Here's what senior SQL interviews ask — ACID, isolation levels, and concurrency problems.
Read guide →08 · 5 min readSQL String & Date Functions — CONCAT, TRIM, DATE_TRUNC & More
String and date manipulation appears in almost every SQL exam. Here's the functions you need to know.
Read guide →Where SQL leads
Certifications that build on SQL
Real proctored exams with published blueprints — each with a free readiness test here that scores you per exam domain rather than giving you one number.
Microsoft AI-103 (Azure AI Apps & Agents)
AI-103’s information extraction domain is retrieval and indexing: semantic, hybrid and vector search for grounding. Querying for the right rows is the skill underneath.