例如：

<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 创建连接
$conn = new mysqli($servername, $username, $password);
// 检查连接
if ($conn->connect_error) {
  die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
?>

创建数据库：

<?php
$servername = "localhost";
$username = "username";
$password = "password";
// 创建连接
$conn = mysqli_connect($servername, $username, $password);
// 检查连接
if (!$conn) {
  die("Connection failed: " . mysqli_connect_error());
}
// 创建数据库
$sql = "CREATE DATABASE myDB";
if (mysqli_query($conn, $sql)) {
  echo "Database created successfully";
} else {
  echo "Error creating database: " . mysqli_error($conn);
}
mysqli_close($conn);
?>