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. 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 | Long term deprecation announced |
| 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 |