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MySQLi vs PDO Prepared Statements: Key Differences and Use Cases in PHP

MySQLi vs PDO Prepared Statements: Key Differences and Use Cases in PHP

February 09, 2025 Education

MySQLi vs PDO Prepared Statements: Key Differences and Use Cases in PHP

When working with PHP, developers often need to interact with databases effectively and securely. Both MySQLi (MySQL Improved) and PDO (PHP Data Objects) provide interfaces for accessing databases, supporting prepared statements to protect against SQL injection and improve performance. However, they differ in several key aspects that are important for making the right choice based on your project requirements.

1. Database Support

MySQLi (MySQL Improved) is specifically designed for MySQL databases. It is limited to MySQL and MariaDB, which means it is not suitable if you plan to switch databases.

, on the other hand, is a more versatile option. As a database abstraction layer, PDO supports multiple database management systems (DBMS), including MySQL, PostgreSQL, SQLite, and many others. This flexibility makes it a more suitable choice if you need to work with different database types in the future.

2. API Style

MySQLi can be used in two ways: procedural and object-oriented. This adaptability might appeal to developers with different coding styles. Here’s a procedural example:

?php
$stmt  mysqli_prepare($conn, SELECT * FROM users WHERE username  ? AND password  ?);
$content
    ?

And here is an object-oriented example:

?php
$stmt  $conn-prepare(SELECT * FROM users WHERE username  ? AND password  ?);
$content
    ?

) is strictly object-oriented, ensuring that developers always use the object-oriented approach. Here’s how you can use PDO:

?php
$stmt  $pdo-prepare(SELECT * FROM users WHERE username  :username AND password  :password);
$content
    ?

3. Named Parameters vs. Positional Parameters

MySQLi primarily uses positional parameters, where you mark placeholders with question marks (?) and bind values in a procedural manner:

?php
$stmt  $conn-prepare(SELECT * FROM users WHERE id  ?);
$stmt-bind_param(i, $id);
$content
    ?

), however, supports both named and positional parameters. For named parameters, use `:name`:

?php
$stmt  $pdo-prepare(SELECT * FROM users WHERE id  :id);
$stmt-bindParam(:id, $id, PDO::PARAM_INT);
$content
    ?

4. Error Handling

MySQLi uses a procedural way to handle errors, requiring you to check the result of each operation:

?php
if (!$stmt  mysqli_prepare($conn, SELECT * FROM users WHERE id  ?)) { 
code
    exit(Prepare failed:  . mysqli_error($conn));
code
}

PDO provides a more robust error handling mechanism through exceptions, allowing for better control over error management:

?php
try {
    $stmt  $pdo-prepare(SELECT * FROM users WHERE id  :id);
    $stmt-execute([:id  $id]);
code
} catch (PDOException $e) {
    echo Error:  . $e-getMessage();
code
}

5. Fetching Data

MySQLi offers methods like `fetch_assoc` and `fetch_row` for fetching results:

?php
while ($row  $stmt-fetch(PDO::FETCH_ASSOC)) { 
code
    // Process the row
code
}

PDO provides a more flexible fetching method using `fetch` with various fetch styles:

?php
while ($row  $stmt-fetch(PDO::FETCH_ASSOC)) { 
code
    // Process the row
code
}

6. Support for Transactions

MySQLi supports transactions but only in the object-oriented mode:

?php
$conn-beginTransaction();
code
    try {
        $stmt1  $conn-prepare(UPDATE users SET balance  ? WHERE id  ?);
        $stmt1-execute([100, 1]);
code
        $stmt2  $conn-prepare(UPDATE orders SET status  ? WHERE user_id  ?);
        $stmt2-execute([shipped, 1]);
code
        $conn-commit();
code
    } catch (PDOException $e) {
        $conn-rollBack();
code
    }
code
}

PDO has built-in support for transactions, allowing for better control over complex database operations:

?php
try {
    $pdo-beginTransaction();
code
    $stmt1  $pdo-prepare(UPDATE users SET balance  ? WHERE id  ?);
    $stmt1-execute([100, 1]);
code
    $stmt2  $pdo-prepare(UPDATE orders SET status  ? WHERE user_id  ?);
    $stmt2-execute([shipped, 1]);
code
    $pdo-commit();
code
} catch (PDOException $e) {
code
    $pdo-rollBack();
code
}

Summary

Choose MySQLi if you are working exclusively with MySQL and prefer a more straightforward approach. MySQLi’s procedural nature and specific focus on MySQL make it simpler for developers familiar with MySQL.

Use PDO if you need flexibility with different databases, prefer object-oriented programming, or require advanced error handling and transaction control. PDO’s support for multiple DBMS and robust error handling makes it a more versatile and future-proof choice.

Overall, while both extensions are effective for working with databases in PHP, your choice may depend on your specific project requirements and database needs. Consider these key differences to make an informed decision for your project.

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