# SQL Joins Practice Pack

Practice prompts for inner joins, left joins, grouping, duplicates, and common reporting mistakes.

## Practice Dataset
- learners(id, full_name, organization)
- courses(id, title, track)
- enrollments(learner_id, course_id, status, enrolled_at)
- quiz_attempts(learner_id, course_id, score, completed_at)

## Prompts
- Return every learner and their active course count, including learners with zero active courses.
- Find courses with enrollments but no quiz attempts in the last 30 days.
- Calculate average quiz score by course and sort from lowest to highest.

## Checks
- Confirm the join key before writing the query.
- Watch for duplicate rows before aggregating.
- Use left joins when the report must include missing activity.

## Related Actions
- Open SQL practice tool: /tools/sql-practice-tools
- View SQL courses: /courses/sql-lab-101