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Oracle AND & OR Operators 🔗

Mentor's Note: Logical operators allow you to build complex rules. Think of AND as a strict gatekeeper (must meet all rules) and OR as a flexible one (any rule will do). 💡

You are looking for a specific candidate. - AND: "I need someone who lives in Surat AND has 5 years of experience." (Very strict). - OR: "I need someone who knows Java OR Python." (More options).

💻 1. The AND Operator

Returns TRUE only if all conditions separated by AND are TRUE.

SELECT first_name, last_name, salary 
FROM employees 
WHERE job_id = 'IT_PROG' 
AND salary > 5000;

💻 2. The OR Operator

Returns TRUE if any of the conditions separated by OR is TRUE.

SELECT first_name, last_name, hire_date
FROM employees 
WHERE department_id = 10 
OR department_id = 20;

🏗️ Architect's Note: Precedence & Parentheses 🛡️

Oracle processes AND before OR. If you mix them without parentheses, your logic might fail! - Rule: Always use ( ) to group your logic. It makes the "Execution Plan" clear to both you and the Oracle Optimizer.

-- ❌ Dangerous: Might return IT_PROG staff OR anyone with high salary
WHERE job_id = 'IT_PROG' OR job_id = 'HR_REP' AND salary > 5000;

-- ✅ Secure: Logic is grouped clearly
WHERE (job_id = 'IT_PROG' OR job_id = 'HR_REP') AND salary > 5000;

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