🟦 TCS (NQT / Technical Round)

👉 Focus: Basics + MCQs + simple coding

🔹 MCQs (Common Pattern)

1. What is the default fetch mode in PDO?
2. Difference between echo and print in PHP?
3. Which is faster: mysqli or PDO? (Tricky ❗)
4. What is the use of LIMIT in SQL?
5. Which function prevents SQL injection?

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🔹 Coding Questions

1. Insert data using PDO

$stmt = $conn->prepare("INSERT INTO users(name,email) VALUES(?,?)");
$stmt->execute([$name,$email]);

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2. Fetch and display users

$stmt = $conn->query("SELECT * FROM users");
$data = $stmt->fetchAll(PDO::FETCH_ASSOC);foreach($data as $row){
    echo $row['name'];
}

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🔹 Theory Questions

• What is CRUD?
• What is Primary Key?
• What is SQL Injection?

👉 TCS Tip: Questions are easy but tricky wording.

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🟪 Wipro (Technical + Coding Round)

👉 Focus: Logic + SQL + real use cases

🔹 SQL Questions

1. Write query to find 2nd highest salary

SELECT MAX(salary) FROM employees 
WHERE salary < (SELECT MAX(salary) FROM employees);

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2. Difference between WHERE and HAVING
   👉 WHERE → before grouping
   👉 HAVING → after grouping

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🔹 Coding Questions

1. Secure Login System (very common 🔥)

$stmt = $conn->prepare("SELECT * FROM users WHERE email=?");
$stmt->execute([$email]);
$user = $stmt->fetch();if($user && password_verify($pass,$user['password'])){
    echo "Login success";
}

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2. Update user data

$stmt = $conn->prepare("UPDATE users SET name=? WHERE id=?");
$stmt->execute([$name,$id]);

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🔹 Scenario Questions

• How will you secure user data?
• How to handle large database?

👉 Wipro Tip: Focus on real-world usage + security

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🟧 Infosys (Technical + HR Round)

👉 Focus: Concepts + scenario-based + clean coding

🔹 Theory Questions

1. What is PDO and why preferred?
2. What is normalization?
3. Explain indexing
4. What are transactions?

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🔹 Coding Questions

1. Pagination (very important 🔥)

$limit = 10;
$offset = 0;$stmt = $conn->prepare("SELECT * FROM users LIMIT ? OFFSET ?");
$stmt->bindValue(1,$limit,PDO::PARAM_INT);
$stmt->bindValue(2,$offset,PDO::PARAM_INT);
$stmt->execute();

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2. JOIN query

SELECT users.name, orders.id
FROM users
INNER JOIN orders ON users.id = orders.user_id;

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🔹 HR + Scenario Questions

• Explain a project you built
• How do you debug errors?
• What if database crashes?

👉 Infosys Tip: Explain logic clearly, not just code.

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🔥 Common Questions Asked in ALL Companies

• What is SQL Injection? How to prevent it?
• Difference between bindParam() and bindValue()
• What is password_hash()?
• What is transaction?
• What is index?

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🎯 Smart Preparation Strategy

• TCS → Practice MCQs + basics
• Wipro → Practice SQL + real coding
• Infosys → Focus on concepts + explanation

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🚀 Final Interview Hack

If asked “How do you secure DB?” say:

“I use PDO prepared statements, input validation, password_hash, and transactions where needed to ensure security and consistency.”