MySQLi vs PDO: When to Choose Each

PDO provides a uniform API across supported drivers; MySQLi specializes in MySQL features.

The examples focus on the operation itself, including the important distinction: Choose by database portability and needed driver-specific features, not a presumed security advantage.

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

Both libraries support prepared statements; driver availability and portability, not a blanket security ranking, determine the choice.

<?php
$available = [
    "PDO MySQL" => extension_loaded("pdo_mysql"),
    "MySQLi" => extension_loaded("mysqli"),
];
foreach ($available as $driver => $installed) {
    echo "$driver: " . ($installed ? "installed" : "missing") . PHP_EOL;
}

Output from a successful local PHP 8.4 run:

PDO MySQL: missing
MySQLi: missing

Example 2: Checking Behavior

Both libraries support prepared statements; driver availability and portability, not a blanket security ranking, determine the choice. Available PDO drivers differ by installed extension.

<?php
$available = [
    "PDO PgSQL" => extension_loaded("pdo_pgsql"),
    "MySQLi" => extension_loaded("mysqli"),
];
foreach ($available as $driver => $installed) {
    echo "$driver: " . ($installed ? "installed" : "missing") . PHP_EOL;
}

Output from a successful local PHP 8.4 run:

PDO PgSQL: missing
MySQLi: missing

Example 3: Practical Example

Both libraries support prepared statements; driver availability and portability, not a blanket security ranking, determine the choice. Available PDO drivers differ by installed extension.

<?php
$available = [
    "PDO SQLite" => extension_loaded("pdo_sqlite"),
    "MySQLi" => extension_loaded("mysqli"),
];
foreach ($available as $driver => $installed) {
    echo "$driver: " . ($installed ? "installed" : "missing") . PHP_EOL;
}

Output from a successful local PHP 8.4 run:

PDO SQLite: missing
MySQLi: missing

Important Behavior and Edge Cases

Both support prepared statements and transactions; neither fixes unsafe dynamic SQL identifiers by itself.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• PDO provides a uniform API across supported drivers; MySQLi specializes in MySQL features.
• Both support prepared statements and transactions; neither fixes unsafe dynamic SQL identifiers by itself.
• Choose by database portability and needed driver-specific features, not a presumed security advantage.

Use MySQLi vs PDO: When to Choose Each when its documented behavior matches the problem. Test the relevant edge cases in your own runtime before deploying it.