| Oracle PL / SQL » Subquery » Subquery Basics |
| 1. | Use sub query as a virtual table | ||
| 2. | Compare with data from subquery | ||
| 3. | An example of a nested three-level subquery | ||
| 4. | If an inner query returns a NULL, the outer query also returns NULL | ||
| 5. | Working with multi-column subqueries | ||
| 6. | Use aggregate function in sub query | ||
| 7. | Sub query: 'SELECT 1 FROM dept d' | ||
| 8. | Using the EXISTS and NOT EXISTS operators | ||
| 9. | Writing Single Row Subqueries | ||
| 10. | Compare with the sub query result | ||
| 11. | Subqueries in a HAVING Clause: Uses a subquery in the HAVING clause of the outer query | ||
| 12. | Subqueries in a FROM Clause (Inline Views) | ||
| 13. | Single Row Subqueries May Return a Maximum of One Row | ||
| 14. | Subqueries May Not Contain an ORDER BY Clause | ||
| 15. | Sub query with table join | ||
| 16. | Writing Multiple Column Subqueries with table join | ||
| 17. | Subquery just returns a literal value: improve performance of your query | ||
| 18. | EXISTS typically offers better performance than IN with subqueries | ||
| 19. | NVL() is used to convert null in correlated query | ||
| 20. | Writing Nested Subqueries | ||
| 21. | subqueries in the SELECT column list (New Way) | ||
| 22. | subqueries in the SELECT column list (Old way) |