Instructions and covered skills
For each question, select the best answer from the four options provided. Read each question carefully and consider the context of relational databases. Turn off notifications and find a quiet environment to focus. Some questions may involve subtle differences between join types. You are allowed to use scratch paper for notes. No external resources or collaboration are permitted.
Key Areas
- Understanding INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN, CROSS JOIN, and self-joins
- Writing multi-table queries with proper ON and USING clauses
- Handling NULLs and filtering results from joined tables
- Applying table aliases for clarity and self-joins
Recommended Preparation
Practice writing SELECT queries that involve two or more tables using sample databases. Familiarize yourself with the differences between join types and when to use each. Review examples of joining tables with multiple conditions and combining JOINs with WHERE clauses. Understand how to use aliases and the implications of join order.