php如何查看mysql数据库版本信息

<?php
$mysqli = new mysqli("localhost", "username", "password", "database");
if ($mysqli->connect_errno) {
    echo "Failed to connect to MySQL: " . $mysqli->connect_error;
    exit();
}
$version = $mysqli->server_info;
echo "MySQL version: " . $version;
$mysqli->close();
?>

<?php
$dsn = 'mysql:host=localhost;dbname=database';
$username = 'username';
$password = 'password';
try {
    $pdo = new PDO($dsn, $username, $password);
    $version = $pdo->getAttribute(PDO::ATTR_SERVER_VERSION);
    echo "MySQL version: " . $version;
} catch (PDOException $e) {
    echo "Failed to connect to MySQL: " . $e->getMessage();
}
?>

<?php
$mysqli = new mysqli("localhost", "username", "password", "database");
if ($mysqli->connect_errno) {
    echo "Failed to connect to MySQL: " . $mysqli->connect_error;
    exit();
}
$result = $mysqli->query("SELECT VERSION()");
$row = $result->fetch_array(MYSQLI_ASSOC);
$version = $row['VERSION()'];
echo "MySQL version: " . $version;
$mysqli->close();
?>