必填字段错误

Question

如果字段未完成，我在显示错误消息时遇到严重问题。 我希望错误消息显示何时抽象是空的，但如果填写，我希望提交按钮转到他们的帐户页面（在会话中） PHP：

session_start();
// this sets variables in the session
$id = $_SESSION['user_id'];
foreach($_POST as $key => $value)
$link = mysql_connect(DB_HOST, DB_USER, DB_PASS) or die("Couldn't make connection.");
$err = array();


if(empty($_SESSION['$user_id']))  // user not logged in; redirect to somewhere else
if (!empty($_POST['doThesis']) && $_POST['doThesis'] == 'Save')
{

list($id) = mysql_fetch_row($result);


/// Automatically collects the hostname or domain  like example.com)
$host  = $_SERVER['HTTP_HOST'];
$host_upper = strtoupper($host);
$path   = rtrim(dirname($_SERVER['PHP_SELF']), '/\\');
if(empty($err)) {

 $sql_insert = "INSERT into `thesis`
(`user_id`,`thesis_Name`,`abstract`  )
VALUES
('$id','$thesis_Name','$abstract') ";

mysql_query($sql_insert,$link) or die("Insertion Failed:" . mysql_error());
}

else{

header("location: myaccount.php?id=" . $_SESSION['user_id']. "");
exit();
}
}
}

在HTML中：

<script>
$(document).ready(function(){
$.validator.addMethod("abstract", function(value, element) {
return this.optional(element) || /^[a-z0-9\_]+$/i.test(value);
}, "Thesis.");
$("#regForm").validate();
});
</script>

<?php
if(!empty($err))  {
echo "<div class=\"msg\">";
foreach ($err as $e) {
echo "* $e <br>";
}
echo "</div>";
}
?>

如果您需要更多信息，请告诉我，因为我需要这项工作！