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21st June, 2026

PHP MySQLi vs PDO – Which Database Extension to Use?

Introduction

When working with databases in PHP, developers face a fundamental choice: MySQLi or PDO. Both are PHP extensions designed to interact with MySQL databases, but they have significant differences that affect your code's flexibility, security, and maintainability. This comprehensive comparison will help you make the right decision for your project with practical code examples and clear explanations.

Quick Overview

MySQLi (MySQL Improved) is a PHP extension specifically designed for MySQL databases. It offers both procedural and object-oriented interfaces and provides access to MySQL-specific features.

PDO (PHP Data Objects) is a database abstraction layer that provides a unified interface for working with multiple database systems. It supports MySQL, PostgreSQL, SQLite, SQL Server, Oracle, and more.

Database Connection Comparison

MySQLi Connection (Object-Oriented):

<?php

// MySQLi OOP connection
$mysqli = new mysqli('localhost', 'root', '', 'my_database');

if ($mysqli->connect_error) {
    die("Connection failed: " . $mysqli->connect_error);
}

echo "MySQLi connected successfully";

?>

MySQLi Connection (Procedural):

<?php

// MySQLi procedural connection
$conn = mysqli_connect('localhost', 'root', '', 'my_database');

if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

echo "MySQLi procedural connected successfully";

?>

PDO Connection:

<?php

// PDO connection with error handling
try {
    $pdo = new PDO(
        "mysql:host=localhost;dbname=my_database;charset=utf8mb4",
        "root",
        "",
        [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_EMULATE_PREPARES => false
        ]
    );
    echo "PDO connected successfully";
} catch (PDOException $e) {
    die("Connection failed: " . $e->getMessage());
}

?>

Key Difference: PDO uses try-catch exception handling by default, making error management cleaner. MySQLi requires manual error checking unless configured for exceptions.

SELECT Query Comparison

MySQLi - Fetch Single Row:

<?php

// MySQLi OOP
$mysqli = new mysqli('localhost', 'root', '', 'my_database');
$stmt = $mysqli->prepare("SELECT id, name, email FROM users WHERE id = ?");
$stmt->bind_param("i", $user_id);
$user_id = 5;
$stmt->execute();
$result = $stmt->get_result();
$user = $result->fetch_assoc();

print_r($user);

$stmt->close();
$mysqli->close();

?>

PDO - Fetch Single Row:

<?php

// PDO
$pdo = new PDO("mysql:host=localhost;dbname=my_database;charset=utf8mb4", "root", "");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$stmt = $pdo->prepare("SELECT id, name, email FROM users WHERE id = :id");
$stmt->execute(['id' => 5]);
$user = $stmt->fetch();

print_r($user);

?>

Key Difference: PDO allows named parameters (:id), making queries more readable. MySQLi uses positional parameters (?) with type-specific binding functions.

INSERT Operation Comparison

MySQLi - Insert Data:

<?php

$mysqli = new mysqli('localhost', 'root', '', 'my_database');

$stmt = $mysqli->prepare("INSERT INTO users (name, email, phone) VALUES (?, ?, ?)");

// Bind parameters with types: s = string, i = integer, d = double, b = blob
$stmt->bind_param("sss", $name, $email, $phone);

$name = "John Doe";
$email = "[email protected]";
$phone = "1234567890";

if ($stmt->execute()) {
    $inserted_id = $stmt->insert_id;
    echo "User created with ID: " . $inserted_id;
} else {
    echo "Error: " . $stmt->error;
}

$stmt->close();
$mysqli->close();

?>

PDO - Insert Data:

<?php

$pdo = new PDO("mysql:host=localhost;dbname=my_database;charset=utf8mb4", "root", "");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$data = [
    'name' => 'Jane Smith',
    'email' => '[email protected]',
    'phone' => '0987654321'
];

$stmt = $pdo->prepare("INSERT INTO users (name, email, phone) VALUES (:name, :email, :phone)");

if ($stmt->execute($data)) {
    $inserted_id = $pdo->lastInsertId();
    echo "User created with ID: " . $inserted_id;
}

?>

Key Difference: PDO's named parameters make the code self-documenting. MySQLi requires remembering the order and types of parameters in bind_param().

UPDATE Operation Comparison

MySQLi - Update:

<?php

$mysqli = new mysqli('localhost', 'root', '', 'my_database');

$stmt = $mysqli->prepare("UPDATE users SET name = ?, email = ?, phone = ? WHERE id = ?");
$stmt->bind_param("sssi", $name, $email, $phone, $id);

$name = "Updated Name";
$email = "[email protected]";
$phone = "5555555555";
$id = 3;

if ($stmt->execute()) {
    if ($stmt->affected_rows > 0) {
        echo "User updated successfully. Rows affected: " . $stmt->affected_rows;
    } else {
        echo "No rows updated. User ID might not exist.";
    }
}

$stmt->close();
$mysqli->close();

?>

PDO - Update:

<?php

$pdo = new PDO("mysql:host=localhost;dbname=my_database;charset=utf8mb4", "root", "");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$data = [
    'name' => 'Updated Name',
    'email' => '[email protected]',
    'phone' => '5555555555',
    'id' => 3
];

$stmt = $pdo->prepare("UPDATE users SET name = :name, email = :email, phone = :phone WHERE id = :id");

$stmt->execute($data);

if ($stmt->rowCount() > 0) {
    echo "User updated successfully. Rows affected: " . $stmt->rowCount();
} else {
    echo "No rows updated. User ID might not exist.";
}

?>

DELETE Operation Comparison

MySQLi - Delete:

<?php

$mysqli = new mysqli('localhost', 'root', '', 'my_database');

$stmt = $mysqli->prepare("DELETE FROM users WHERE id = ?");
$stmt->bind_param("i", $id);
$id = 3;

if ($stmt->execute()) {
    echo "User deleted successfully";
}

$stmt->close();
$mysqli->close();

?>

PDO - Delete:

<?php

$pdo = new PDO("mysql:host=localhost;dbname=my_database;charset=utf8mb4", "root", "");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$stmt = $pdo->prepare("DELETE FROM users WHERE id = :id");
$stmt->execute(['id' => 3]);

echo "User deleted successfully";

?>

Fetching Multiple Rows Comparison

MySQLi - Get All Rows:

<?php

$mysqli = new mysqli('localhost', 'root', '', 'my_database');

$stmt = $mysqli->prepare("SELECT id, name, email FROM users ORDER BY id DESC LIMIT 10");
$stmt->execute();
$result = $stmt->get_result();
$users = $result->fetch_all(MYSQLI_ASSOC);

foreach ($users as $user) {
    echo $user['name'] . " - " . $user['email'] . "<br>";
}

$stmt->close();

?>

PDO - Get All Rows:

<?php

$pdo = new PDO("mysql:host=localhost;dbname=my_database;charset=utf8mb4", "root", "");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$stmt = $pdo->prepare("SELECT id, name, email FROM users ORDER BY id DESC LIMIT 10");
$stmt->execute();
$users = $stmt->fetchAll();

foreach ($users as $user) {
    echo $user['name'] . " - " . $user['email'] . "<br>";
}

?>

Transaction Handling

MySQLi - Transactions:

<?php

$mysqli = new mysqli('localhost', 'root', '', 'my_database');

try {
    $mysqli->begin_transaction();

    // First query
    $stmt1 = $mysqli->prepare("UPDATE accounts SET balance = balance - 500 WHERE id = ?");
    $stmt1->bind_param("i", $from_account);
    $from_account = 1;
    $stmt1->execute();

    // Second query
    $stmt2 = $mysqli->prepare("UPDATE accounts SET balance = balance + 500 WHERE id = ?");
    $stmt2->bind_param("i", $to_account);
    $to_account = 2;
    $stmt2->execute();

    $mysqli->commit();
    echo "Transaction completed successfully";

} catch (Exception $e) {
    $mysqli->rollback();
    echo "Transaction failed: " . $e->getMessage();
}

$mysqli->close();

?>

PDO - Transactions:

<?php

$pdo = new PDO("mysql:host=localhost;dbname=my_database;charset=utf8mb4", "root", "");
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

try {
    $pdo->beginTransaction();

    $stmt1 = $pdo->prepare("UPDATE accounts SET balance = balance - 500 WHERE id = :from_id");
    $stmt1->execute(['from_id' => 1]);

    $stmt2 = $pdo->prepare("UPDATE accounts SET balance = balance + 500 WHERE id = :to_id");
    $stmt2->execute(['to_id' => 2]);

    $pdo->commit();
    echo "Transaction completed successfully";

} catch (Exception $e) {
    $pdo->rollback();
    echo "Transaction failed: " . $e->getMessage();
}

?>

Error Handling Comparison

MySQLi Error Handling:

<?php

// Manual error checking approach
$mysqli = new mysqli('localhost', 'root', '', 'my_database');

if ($mysqli->connect_error) {
    error_log("Connection Error: " . $mysqli->connect_error);
    die("Database connection error. Please try later.");
}

$stmt = $mysqli->prepare("SELECT * FROM non_existent_table");

if (!$stmt) {
    error_log("Query Error: " . $mysqli->error);
    die("Query preparation failed.");
}

// Enable MySQLi exceptions (alternative)
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

try {
    $mysqli = new mysqli('localhost', 'root', '', 'my_database');
    $stmt = $mysqli->prepare("SELECT * FROM non_existent_table");
} catch (mysqli_sql_exception $e) {
    error_log("MySQLi Error: " . $e->getMessage());
    die("An error occurred.");
}

?>

PDO Error Handling:

<?php

// PDO uses exceptions by default when configured
try {
    $pdo = new PDO("mysql:host=localhost;dbname=my_database", "root", "", [
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
    ]);
    
    $stmt = $pdo->prepare("SELECT * FROM non_existent_table");
    $stmt->execute();
    
} catch (PDOException $e) {
    error_log("PDO Error: " . $e->getMessage());
    die("An error occurred. Please try later.");
}

?>

Key Difference: PDO throws exceptions automatically when configured. MySQLi requires either manual error checking or explicit configuration for exceptions.

Database Driver Support

This is where PDO truly shines. The exact same code works across different databases:

<?php

// PDO - Switch database by changing only the DSN string

// MySQL
$pdo = new PDO("mysql:host=localhost;dbname=mydb", "root", "");

// PostgreSQL
$pdo = new PDO("pgsql:host=localhost;dbname=mydb", "postgres", "password");

// SQLite
$pdo = new PDO("sqlite:/path/to/database.db");

// SQL Server
$pdo = new PDO("sqlsrv:server=localhost;database=mydb", "sa", "password");

// The rest of your code remains exactly the same!
$stmt = $pdo->prepare("SELECT * FROM users WHERE id = :id");
$stmt->execute(['id' => 5]);
$user = $stmt->fetch();

?>

With MySQLi, you would need to rewrite all database interaction code if you ever switch from MySQL to another database system.

Prepared Statements Security

Both extensions support prepared statements which prevent SQL injection. Here's how they handle it differently:

MySQLi Prepared Statement with Multiple Inserts:

<?php

$mysqli = new mysqli('localhost', 'root', '', 'my_database');

$stmt = $mysqli->prepare("INSERT INTO users (name, email) VALUES (?, ?)");

$users = [
    ['Alice', '[email protected]'],
    ['Bob', '[email protected]'],
    ['Charlie', '[email protected]']
];

foreach ($users as $user) {
    $stmt->bind_param("ss", $user[0], $user[1]);
    $stmt->execute();
}

$stmt->close();
$mysqli->close();

?>

PDO Prepared Statement with Multiple Inserts:

<?php

$pdo = new PDO("mysql:host=localhost;dbname=my_database", "root", "", [
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
]);

$stmt = $pdo->prepare("INSERT INTO users (name, email) VALUES (:name, :email)");

$users = [
    ['name' => 'Alice', 'email' => '[email protected]'],
    ['name' => 'Bob', 'email' => '[email protected]'],
    ['name' => 'Charlie', 'email' => '[email protected]']
];

foreach ($users as $user) {
    $stmt->execute($user);
}

?>

Key Difference: PDO allows passing the data array directly to execute(), making the code cleaner. MySQLi requires individual bind_param() calls for each execution.

Performance Comparison

In terms of raw performance, MySQLi is slightly faster than PDO for MySQL-specific operations because it doesn't have the abstraction overhead. However, the difference is negligible in real-world applications — typically less than 5%.

// Performance test (conceptual result for 1000 queries)
MySQLi:  0.042 seconds
PDO:     0.047 seconds
Difference: ~5ms for 1000 operations (negligible)

For most applications, choosing based on features and flexibility is more important than the tiny performance difference.

When to Use MySQLi

Use MySQLi when:

You're absolutely sure you'll only ever use MySQL/MariaDB
You need MySQL-specific features like mysqli_multi_query() or async queries
You prefer procedural programming style
You're maintaining legacy code that already uses MySQLi
You need direct access to MySQL connection statistics

MySQLi-Specific Feature Example:

<?php

$mysqli = new mysqli('localhost', 'root', '', 'my_database');

// MySQLi multiple queries (not available in PDO)
$sql = "SELECT COUNT(*) FROM users; SELECT COUNT(*) FROM orders; SELECT COUNT(*) FROM products;";

if ($mysqli->multi_query($sql)) {
    do {
        if ($result = $mysqli->store_result()) {
            $row = $result->fetch_row();
            echo "Count: " . $row[0] . "<br>";
            $result->free();
        }
    } while ($mysqli->next_result());
}

// Get connection stats (MySQLi only)
$stats = $mysqli->stat();
echo "Connection stats: " . $stats;

$mysqli->close();

?>

When to Use PDO

Use PDO when:

You might switch databases in the future
You want cleaner syntax with named parameters
You prefer object-oriented programming
You need better error handling with exceptions
You want the flexibility of working with multiple database systems
You're building a framework or library used by others
You value code portability

Quick Decision Guide

Choose PDO if:

You're starting a new project
You want the most flexible solution
You value clean, readable code
You might deploy to different environments
You prefer modern exception handling

Choose MySQLi if:

You're working with an existing MySQLi codebase
You need MySQL-specific features
You prefer procedural programming
Raw performance is absolutely critical (rare)

Migration Example: MySQLi to PDO

If you decide to switch from MySQLi to PDO, here's how the conversion looks:

Before (MySQLi):

<?php

$mysqli = new mysqli('localhost', 'root', '', 'my_database');
$stmt = $mysqli->prepare("SELECT * FROM users WHERE email = ? AND status = ?");
$stmt->bind_param("si", $email, $status);
$email = "[email protected]";
$status = 1;
$stmt->execute();
$result = $stmt->get_result();
$user = $result->fetch_assoc();

?>

After (PDO):

<?php

$pdo = new PDO("mysql:host=localhost;dbname=my_database", "root", "");
$stmt = $pdo->prepare("SELECT * FROM users WHERE email = :email AND status = :status");
$stmt->execute([
    'email' => '[email protected]',
    'status' => 1
]);
$user = $stmt->fetch();

?>

Conclusion

Both MySQLi and PDO are excellent choices for database interaction in PHP, but they serve different needs. PDO is the recommended choice for most new projects due to its database portability, cleaner syntax, named parameters, and superior error handling. MySQLi remains valuable when you need MySQL-specific features or are maintaining existing code. The key takeaway is that both extensions support prepared statements and secure database operations — the choice comes down to your specific project requirements and coding preferences. If in doubt, choose PDO for maximum flexibility and future-proofing.

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