1. What is Oracle?

Oracle Database is a powerful relational database management system (RDBMS) developed by Oracle Corporation. It is widely used for enterprise applications.

• Highly secure and scalable
• Supports large volumes of data
• Used in banking, ERP, and large systems

2. Oracle Database Architecture

• Database – Physical data files
• Instance – Memory and background processes
• Tablespaces – Logical storage units
• Datafiles – Store actual data

3. Installing Oracle

You can use:

• Oracle Database Express Edition (XE)
• Oracle Live SQL (Online)
• Oracle SQL Developer

4. SQL Basics

SQL (Structured Query Language) is used to interact with Oracle databases.

SELECT * FROM employees;

5. Creating Tables

CREATE TABLE employees (
  emp_id NUMBER PRIMARY KEY,
  name VARCHAR2(50),
  salary NUMBER,
  hire_date DATE
);

6. Inserting Data

INSERT INTO employees VALUES (
  1,
  'John Doe',
  50000,
  SYSDATE
);

7. Selecting Data

SELECT name, salary
FROM employees
WHERE salary > 40000;

8. Updating Data

UPDATE employees
SET salary = 55000
WHERE emp_id = 1;

9. Deleting Data

DELETE FROM employees
WHERE emp_id = 1;

10. Constraints

• PRIMARY KEY
• FOREIGN KEY
• UNIQUE
• NOT NULL
• CHECK

salary NUMBER CHECK (salary > 0)

11. Joins

SELECT e.name, d.department_name
FROM employees e
JOIN departments d
ON e.dept_id = d.dept_id;

12. Introduction to PL/SQL

PL/SQL is Oracle’s procedural extension of SQL.

BEGIN
  DBMS_OUTPUT.PUT_LINE('Hello Oracle');
END;
/

13. Stored Procedures

CREATE OR REPLACE PROCEDURE show_message AS
BEGIN
  DBMS_OUTPUT.PUT_LINE('Welcome to Oracle');
END;
/

14. Oracle Security

• Users and roles
• Privileges
• Auditing

GRANT SELECT ON employees TO user1;

15. Career Paths with Oracle

• Oracle SQL Developer
• Oracle DBA
• PL/SQL Developer
• Data Engineer

16. Conclusion

Oracle Database is a robust enterprise solution. Learning SQL and PL/SQL opens doors to high-demand roles.