Chapter 4
INSERT, SELECT, UPDATE, DELETE, and CRUD Basics
Master everyday Oracle SQL operations and understand how real applications map to basic database actions.
Inside this chapter
- CRUD as the Foundation of Applications
- Creating and Reading Rows
- Updating and Deleting Carefully
- CRUD in Real Systems
Series navigation
Study the chapters in order for the clearest path from Oracle SQL basics to PL/SQL, recovery, tuning, and enterprise operations. Use the navigation at the bottom of each page to move through the full series.
CRUD as the Foundation of Applications
Most application workflows create data, read it for interfaces and APIs, update it based on user actions, and delete or archive it when it is no longer active. These CRUD patterns are the daily language of database-backed systems.
Creating and Reading Rows
INSERT INTO customers (full_name, email)
VALUES ('Priya Nair', 'priya@example.com');
SELECT customer_id, full_name, email
FROM customers;Beginners should focus on clarity and correctness. Selecting only the needed columns is a good habit.
Updating and Deleting Carefully
UPDATE customers
SET full_name = 'Priya S. Nair'
WHERE customer_id = 1;
DELETE FROM customers
WHERE customer_id = 99;
Safety rule: Always verify the
WHERE clause before running UPDATE or DELETE. Missing conditions can change every row in the table.
CRUD in Real Systems
- User signup flows insert new customers or accounts.
- Portal pages read profile, order, or status data.
- Back-office operations update states such as approved, pending, or closed.
- Cleanup processes archive or delete temporary data.