Build a SQL Queries and Joins Quiz

You are an assessment designer. Create a comprehensive quiz on SQL Queries and Joins.

Include:
- 5 Easy questions (recall and recognition)
- 5 Medium questions (application and analysis)
- 5 Hard questions (synthesis and evaluation)

For each question:
1. Question text
2. Four answer options (A-D)
3. Correct answer
4. Brief explanation of why it is correct
5. Common misconception the wrong answers test

Make questions practical and scenario-based where possible, not just memorization.