Why PDO is the standard in PHP - Challenge Your Understanding

Challenge - 5 Problems

🧠 Conceptual

intermediate

Why use PDO for database access?

Which of the following is the main reason PDO is considered the standard for database access in PHP?

A PDO only works with MySQL databases.

B PDO automatically caches all queries for faster performance.

C PDO requires no configuration to connect to any database.

D PDO supports multiple database types with the same interface.

💡 Hint

Think about how PDO helps when switching databases.

PDO provides a consistent interface to many different databases, so you can switch databases without rewriting all your code.

❓ Predict Output

intermediate

PDO prepared statement output

What will be the output of this PHP code using PDO prepared statements?

PHP

<?php
$pdo = new PDO('sqlite::memory:');
$pdo->exec('CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)');
$stmt = $pdo->prepare('INSERT INTO users (name) VALUES (:name)');
$stmt->execute(['name' => 'Alice']);
$stmt->execute(['name' => 'Bob']);
$count = $pdo->query('SELECT COUNT(*) FROM users')->fetchColumn();
echo $count;
?>

A 2

B 1

C 0

D SyntaxError

💡 Hint

Count how many rows were inserted.

The code inserts two users, so the count is 2.

❓ Predict Output

advanced

PDO error mode behavior

What error behavior will this PDO code produce?

PHP

<?php
$pdo = new PDO('sqlite::memory:');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
try {
    $pdo->exec('INVALID SQL');
    echo 'Success';
} catch (PDOException $e) {
    echo 'Error caught';
}
?>

A Success

B No output

C Error caught

D Fatal error

💡 Hint

Check how PDO handles errors with ERRMODE_EXCEPTION.

PDO throws an exception on invalid SQL when ERRMODE_EXCEPTION is set, so the catch block runs.

🧠 Conceptual

advanced

Why is PDO safer than direct queries?

Which feature of PDO helps prevent SQL injection attacks?

A Use of prepared statements with bound parameters.

B Limiting database user permissions by default.

C Automatic encryption of all data sent to the database.

D Caching query results to avoid repeated queries.

💡 Hint

Think about how user input is handled safely.

Prepared statements separate code from data, preventing malicious input from changing the query structure.

🧠 Conceptual

expert

PDO and database portability

Which statement best explains how PDO improves database portability in PHP applications?

A PDO stores all data in a single file format compatible with all databases.

B PDO provides a uniform API that works with many database systems, reducing code changes when switching databases.

C PDO requires no SQL knowledge because it uses a visual query builder internally.

D PDO automatically converts all SQL queries to the syntax of the target database.

💡 Hint

Consider how PDO abstracts database differences.

PDO offers a consistent interface for different databases, so you only need to change the connection string, not the query code.