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A free SQL tutorial in short lessons on one shop database. Every example runs on real PostgreSQL in your browser, and the page checks your answers.
DbSchema Blog
Database design, migrations, SQL and everyday database work — explained with practical examples.
SQL GROUP BY Statement Explained with Examples | DbSchema
Learn SQL GROUP BY with single and multi-column examples, HAVING, JOINs, aggregations, and common mistakes.
SQL GROUP BY Explained with Examples | DbSchema
Learn SQL GROUP BY with clear examples for COUNT, SUM, AVG, HAVING, and JOIN-based reporting queries.
SQL BETWEEN Operator Explained with Range Examples | DbSchema
Learn SQL BETWEEN and NOT BETWEEN with numeric, date, text, and time examples, plus common mistakes and best practices.
How to Create Custom Data Types in DbSchema
Create custom data types in DbSchema’s Logical Design to standardize columns; on deployment they convert to native DBMS types like VARCHAR.
What Is an Index in MongoDB? Beginner Guide with Examples
Learn what an index is in MongoDB, why it matters, and how to use it. This beginner tutorial explains single-field, compound, and text indexes with examples in MongoDB shell and DbSchema.
MongoDB Diagram Design and Visualization with DbSchema
Learn how to create diagrams for MongoDB, implement validation rules and visually manage MongoDB databases.
MongoDB Aggregation Pipeline Tutorial for Beginners in 2025
Understand MongoDB aggregation pipelines with clear examples. Learn how to filter, group, sort, and transform data step by step in this beginner-friendly guide.
MongoDB Schema Design Best Practices for 2026
Learn the best MongoDB schema design practices for 2026, common mistakes to avoid, and how DbSchema helps visualize, document, and optimize your collections.
MongoDB Validation Rules Explained with Examples | DbSchema
How MongoDB validation rules work: a $jsonSchema validator in mongosh, the validationLevel and validationAction settings, and the same rule designed in DbSchema.
MongoDB Embedded Documents and Arrays, With Query Examples
What an embedded document and an array field are in MongoDB, with minimal examples, dot-notation queries, $elemMatch, and multikey indexes on array fields.