PHP offers three different APIs to connect to MySQL. Below we show the APIs provided by the mysql, mysqli, and PDO extensions. Each code snippet creates a connection to a MySQL server running on "example.com" using the username "user" and the password "password". And a query is run to greet the user.
Example #1 Comparing the three MySQL APIs
<?php
// mysqli
$mysqli = new mysqli("example.com", "user", "password", "database");
$result = $mysqli->query("SELECT 'Hello, dear MySQL user!' AS _message FROM DUAL");
$row = $result->fetch_assoc();
echo htmlentities($row['_message']);
// PDO
$pdo = new PDO('mysql:host=example.com;dbname=database', 'user', 'password');
$statement = $pdo->query("SELECT 'Hello, dear MySQL user!' AS _message FROM DUAL");
$row = $statement->fetch(PDO::FETCH_ASSOC);
echo htmlentities($row['_message']);
// mysql
$c = mysql_connect("example.com", "user", "password");
mysql_select_db("database");
$result = mysql_query("SELECT 'Hello, dear MySQL user!' AS _message FROM DUAL");
$row = mysql_fetch_assoc($result);
echo htmlentities($row['_message']);
?>
Recommended API
It is recommended to use either the mysqli or PDO_MySQL extensions. It is not recommended to use the old mysql extension for new development, as it has been deprecated as of PHP 5.5.0 and will be removed in the future. A detailed feature comparison matrix is provided below. The overall performance of all three extensions is considered to be about the same. Although the performance of the extension contributes only a fraction of the total run time of a PHP web request. Often, the impact is as low as 0.1%.
Feature comparison
| ext/mysqli | PDO_MySQL | ext/mysql | |
|---|---|---|---|
| PHP version introduced | 5.0 | 5.1 | 2.0 |
| Included with PHP 5.x | Yes | Yes | Yes |
| Development status | Active | Active | Maintenance only |
| Lifecycle | Active | Active | Deprecated |
| Recommended for new projects | Yes | Yes | No |
| OOP Interface | Yes | Yes | No |
| Procedural Interface | Yes | No | Yes |
| API supports non-blocking, asynchronous queries with mysqlnd | Yes | No | No |
| Persistent Connections | Yes | Yes | Yes |
| API supports Charsets | Yes | Yes | Yes |
| API supports server-side Prepared Statements | Yes | Yes | No |
| API supports client-side Prepared Statements | No | Yes | No |
| API supports Stored Procedures | Yes | Yes | No |
| API supports Multiple Statements | Yes | Most | No |
| API supports Transactions | Yes | Yes | No |
| Transactions can be controlled with SQL | Yes | Yes | Yes |
| Supports all MySQL 5.1+ functionality | Yes | Most | No |