Error handling with PDO exceptions in PHP - Mini Project: Build & Apply

Error handling with PDO exceptions

📖 Scenario: You are building a simple PHP script to connect to a database and fetch user data. Sometimes, the connection or query might fail. To handle these problems safely, you will use PDO exceptions.

🎯 Goal: Create a PHP script that connects to a database using PDO, runs a query to get user names, and handles any errors using PDO exceptions.

📋 What You'll Learn

Create a PDO connection to a MySQL database with given credentials.

Set the PDO error mode to throw exceptions.

Write a try-catch block to catch PDO exceptions.

Run a simple SELECT query to get user names from a table called users.

Print the user names if the query succeeds.

Print an error message if an exception occurs.

💡 Why This Matters

🌍 Real World

Handling database errors gracefully is important in real web applications to avoid crashes and show friendly messages.

💼 Career

Knowing how to use PDO exceptions is a key skill for PHP developers working with databases securely and reliably.

1

Create a PDO connection

Create a new PDO object called $pdo to connect to a MySQL database with these exact details: host localhost, database name testdb, username root, and password password123.

PHP

<?php
// Create a new PDO connection to MySQL
// Your code here

Need a hint?

Use new PDO() with the DSN string and credentials exactly as given.

2

Set PDO error mode to exceptions

Set the PDO attribute PDO::ATTR_ERRMODE on $pdo to PDO::ERRMODE_EXCEPTION using the setAttribute method.

PHP

<?php
$pdo = new PDO('mysql:host=localhost;dbname=testdb', 'root', 'password123');
// Set PDO error mode to exceptions
// Your code here

Need a hint?

Use $pdo->setAttribute() to set the error mode.

3

Write try-catch block with query

Write a try block where you run the query SELECT name FROM users using $pdo->query() and fetch all results with fetchAll(PDO::FETCH_ASSOC) into a variable called $users. Then write a catch block to catch PDOException as $e.

PHP

setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// Add try-catch block to run query and catch exceptions
// Your code here

Need a hint?

Use try { ... } catch (PDOException $e) { ... } and run the query inside the try block.

4

Print results or error message

Inside the try block, use a foreach loop with variables $user to print each user name with echo $user['name'] . "\n";. Inside the catch block, print the error message with echo "Error: " . $e->getMessage();.

PHP

setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

try {
    $stmt = $pdo->query('SELECT name FROM users');
    $users = $stmt->fetchAll(PDO::FETCH_ASSOC);
    // Print each user name
    // Your code here
} catch (PDOException $e) {
    // Print error message
    // Your code here
}

Need a hint?

Use foreach ($users as $user) to print names and echo "Error: " . $e->getMessage(); in catch.