PHP-mysqli出错回显

面向对象风格

    connect_errno) {
            printf("connect filed: $s \n", $conn->connect_error);
            exit;
        }

        if(!$conn->query("SET a=1")) {
            printf("error message: %s\n", $conn->error);
        }
    ?>

面向过程风格

From: http://php.net/manual/zh/mysqli.error.php