如何用php建立数据库

$servername = "localhost";
$username = "root";
$password = "password";
$conn = new PDO("mysql:host=$servername;dbname=db_name", $username, $password);

$sql = "CREATE DATABASE db_name";
$conn->query($sql);

$sql = "CREATE TABLE table_name (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL,
age INT(3) UNSIGNED NOT NULL
)";
$conn->query($sql);

$sql = "INSERT INTO table_name (name, age) VALUES (?, ?)";
$stmt = $conn->prepare($sql);
$stmt->bind_param("ss", $name, $age);
$name = "John Doe";
$age = 30;
$stmt->execute();

$sql = "SELECT * FROM table_name";
$stmt = $conn->query($sql);
while ($row = $stmt->fetch_assoc()) {
    echo $row['name'] . '<br>';
}

$sql = "UPDATE table_name SET name = ? WHERE id = ?";
$stmt = $conn->prepare($sql);
$stmt->bind_param("si", $name, $id);
$name = "John Smith";
$id = 1;
$stmt->execute();

$sql = "DELETE FROM table_name WHERE id = ?";
$stmt = $conn->prepare($sql);
$stmt->bind_param("i", $id);
$id = 1;
$stmt->execute();

$conn->close();