Learn SQL
From SELECT and filtering to joins, grouping and NULL semantics, these quizzes emphasise reading queries and predicting their results.
What you will practise
- Filtering and sorting
- Joins and their edge cases
- GROUP BY and HAVING
- NULL behaviour
Roadmap
Work through the levels in order, or jump to where you are.
SQL quizzes
Interactive SQL challenges
Hands-on activities: find bugs, complete code, order steps and match concepts.
SQL articles
SQL Practice Questions with Solutions for Beginners
Nine hands-on SQL exercises on a small student database, from filtering and grouping to joins and safe updates, each with a worked solution and the reasoning behind it.
SQL Indexes Explained: How They Speed Up Queries and When They Do Not
What a database index is, how it speeds up lookups, what it costs on writes, how to choose columns and column order, and how to check whether a query really uses an index.
SQL Joins Explained with Real Questions
INNER, LEFT and anti-joins explained through the question each one answers, plus the WHERE-versus-ON mistake that silently drops rows.
FAQ
Which SQL dialect is used?
Standard SQL. Where MySQL and PostgreSQL differ, the explanation notes it.
Are these quizzes good for Data Analyst interviews?
Yes. Joins, GROUP BY, HAVING, and subqueries are the most frequently asked concepts in data analyst SQL rounds.
Do you cover database design or normalization?
Currently, the focus is on querying existing data (DML). Normalization and schema design (DDL) are planned for future Expert-level modules.
Is NoSQL covered here?
No. SQL covers relational databases. For NoSQL concepts, please check our MongoDB roadmap.