Partagez deux méthodes de connexion à MySQL en PHP7

/*
 * mysqli
 * 数据库地址，登陆账号，密码，数据库名称
 */
    $mysqli = new mysqli("localhost", "root", "", "student");
    $sql = "SELECT * FROM tb_user";
    $result = $mysqli->query($sql);
    $row = $result->fetch_assoc(); // 从结果集中取得一行作为关联数组
    echo $row["password"];
    /* free result set */
    $result->free();  
    /* close connection */
    $mysqli->close();

/*
 * 第一个参数是mysql:host,第二是dbname,第三个账户名，第四个密码
 */
try {
    $pdo = new PDO("mysql:host=localhost;dbname=student", "root", "");
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}
$sql = "select * from tb_user";
echo $sql . "<BR>";
$pdo->query(&#39;set names utf8;&#39;);
$result = $pdo->query($sql);
$rows = $result->fetchAll();
foreach ($rows as $row) {
    $username = $row[1];
    $pwd = $row[2];
    echo $username;
}