Connecting to MySQL with PDO

PDO provides exception-driven database access through a MySQL DSN and prepared statements.

The examples focus on the operation itself, including the important distinction: MySQLi is another MySQL-specific option; PDO is driver-based.

What It Does

Use the examples below to observe the behavior on a small dataset before extending it to application code.

Before You Start

The examples use PHP 8.2+ features where shown. Database snippets require the corresponding PDO driver, demo tables, and credentials configured outside source code.

Example 1: Basic Use

Connecting is only the first step: use bound parameters for later queries.

<?php
$pdo = new PDO(
    "mysql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo") . ";charset=utf8mb4",
    getenv("DB_USER") ?: "app",
    getenv("DB_PASSWORD") ?: "",
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_EMULATE_PREPARES => false]
);
$stmt = $pdo->prepare("SELECT email FROM users WHERE active = :active ORDER BY id LIMIT 5");
$stmt->execute(["active" => 1]);
echo json_encode($stmt->fetchAll(PDO::FETCH_ASSOC));

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Example 2: Checking Behavior

Connecting is only the first step: use bound parameters for later queries. Named bound filters can be combined after connecting.

<?php
$pdo = new PDO(
    "mysql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo") . ";charset=utf8mb4",
    getenv("DB_USER") ?: "app",
    getenv("DB_PASSWORD") ?: "",
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_EMULATE_PREPARES => false]
);
$stmt = $pdo->prepare("SELECT email FROM users WHERE active = :active AND id > :min ORDER BY id LIMIT 5");
$stmt->execute(["active" => 1, "min" => 10]);
echo json_encode($stmt->fetchAll(PDO::FETCH_ASSOC));

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Example 3: Practical Example

Connecting is only the first step: use bound parameters for later queries. Named bound filters can be combined after connecting.

<?php
$pdo = new PDO(
    "mysql:host=" . (getenv("DB_HOST") ?: "127.0.0.1") . ";dbname=" . (getenv("DB_NAME") ?: "demo") . ";charset=utf8mb4",
    getenv("DB_USER") ?: "app",
    getenv("DB_PASSWORD") ?: "",
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_EMULATE_PREPARES => false]
);
$stmt = $pdo->prepare("SELECT email FROM users WHERE active = :active AND id > :min ORDER BY id LIMIT 5");
$stmt->execute(["active" => 1, "min" => 20]);
echo json_encode($stmt->fetchAll(PDO::FETCH_ASSOC));

This example is meant for a configured application environment; output depends on the installed extension, external service, or database contents.

Important Behavior and Edge Cases

Do not embed production passwords directly in scripts or interpolate user input into SQL.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• PDO provides exception-driven database access through a MySQL DSN and prepared statements.
• Do not embed production passwords directly in scripts or interpolate user input into SQL.
• MySQLi is another MySQL-specific option; PDO is driver-based.

Use Connecting to MySQL with PDO when its documented behavior matches the problem. Test the relevant edge cases in your own runtime before deploying it.