Multi-Table JOINs & GROUP BY Aggregations
Combine tables using INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN, and summarize data with GROUP BY & HAVING.
SQL JOIN Types & Grouping Rules
### SQL JOIN Venn Matrix
- **INNER JOIN**: Returns only matching rows present in BOTH tables.
- **LEFT JOIN**: Returns ALL rows from the left table, plus matched right table rows (filling missing values with `NULL`).
- **GROUP BY & HAVING**: Aggregates row values (`SUM`, `AVG`, `COUNT`, `MAX`). The `HAVING` clause filters AFTER group aggregation.
