能获取信息，但修改之后会提示修改失败

<?php

require_once('../connect.php');

$id = $_POST['id'];

$title = $_POST['title'];

$author = $_POST['author'];

$description = $_POST['description'];

$content = $_POST['content'];

$dateline = time();

$updatesql = "update article set title=$title, author=$author, description=$description, content=$content, dateline=$dateline where id=$id";

if (mysqli_query($con, $updatesql)) {

echo "<script>alert('修改成功'); window.location.href='article.manage.php'</script>";

} else {

echo "<script>alert('修改失败'); window.location.href='article.manage.php'</script>";

}

?>