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.
SQL 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.
SQL 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.
SQL 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.
SQL Window Functions — ROW_NUMBER, RANK, LEAD, LAG with Examples
Window functions are the most powerful — and most-tested — advanced SQL feature. Here's everything you need to know.
SQL 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.
SQL Transactions Explained — ACID Properties and Isolation Levels
Transactions ensure data integrity. Here's what senior SQL interviews ask — ACID, isolation levels, and concurrency problems.
SQL 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.
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