<?php
$servername = "localhost";
$username = "username";
$password = "password";
 
// 创建连接
$conn = new mysqli($servername, $username, $password);
 
// 检测连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
} 
echo "连接成功";
?>

<?php
$servername = "localhost";
$username = "username";
$password = "password";
 
try {
    $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password);
    echo "连接成功"; 
}
catch(PDOException $e)
{
    echo $e->getMessage();
}
?>

实例 (MySQLi - 面向对象)
$conn->close();

实例 (MySQLi - 面向过程)
mysqli_close($conn);

实例 (PDO)
$conn = null;

实例 (MySQLi - 面向对象)
<?php
$servername = "localhost";
$username = "username";
$password = "password";

// 创建连接
$conn = new mysqli($servername, $username, $password);
// 检测连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
} 

// 创建数据库
$sql = "CREATE DATABASE myDB";
if ($conn->query($sql) === TRUE) {
    echo "数据库创建成功";
} else {
    echo "Error creating database: " . $conn->error;
}

$conn->close();
?>

实例 (MySQLi Procedural)
<?php
$servername = "localhost";
$username = "username";
$password = "password";

// 创建连接
$conn = mysqli_connect($servername, $username, $password);
// 检测连接
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}

// 创建数据库
$sql = "CREATE DATABASE myDB";
if (mysqli_query($conn, $sql)) {
    echo "数据库创建成功";
} else {
    echo "Error creating database: " . mysqli_error($conn);
}

mysqli_close($conn);
?>

使用 PDO：
<?php 
$servername = "localhost"; 
$username = "username"; 
$password = "password"; 

try { 
    $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password); 

    // 设置 PDO 错误模式为异常 
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); 
    $sql = "CREATE DATABASE myDBPDO"; 

    // 使用 exec() ，因为没有结果返回 
    $conn->exec($sql); 

    echo "数据库创建成功<br>"; 
} 
catch(PDOException $e) 
{ 
    echo $sql . "<br>" . $e->getMessage(); 
} 

$conn = null; 
?>