我是PHP的新手，在这里遇到麻烦，我不知道为什么它不保存表单数据，如果你发现错误请帮助我。我已经尝试了很多编辑，但它根本不起作用。提前谢谢。
<?php
session_start();
if(!$_SESSION['username'])
{
header("Location: index.php");//redirect to login page to secure the welcome page without login access.
}
?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Registeration Form</title>
<link rel="stylesheet" type="text/css" href="css/view.css" media="all">
<script type="text/javascript" src="js/view.js"></script>
<script type="text/JavaScript" src="js/forms.js"></script>
</head>
<body id="main_body" >
<img id="top" src="images/top.png" alt="">
<div id="form_container">
<h1>Registeration Form</h1>
<div id="wrap">
<!-- Here's all it takes to make this navigation bar. -->
<ul id="nav">
<li><a href="manage.php">Home</a></li>
<li><a href="register.php">Register</a></li>
<li><a href="#">Edit</a></li>
<li><a href="#">View</a></li>
<li><a href="#">Delete</a></li>
<li><a href="logout.php">Logout</a></li>
</ul>
<!-- That's it! -->
</div>
<form action="<?=$_SERVER['PHP_SELF']?>" method="POST" class="appnitro">
<div class="form_description">
<h2>Registeration Form</h2>
<p>Please fill the form</p>
</div>
<label class="description">Name </label>
<input name="name" class="element text medium" type="text" maxlength="255" value=""/>
<label class="description">Email </label>
<input name="email" class="element text medium" type="text" maxlength="255" value=""/>
<label class="description" >Department </label>
<input name="department" class="element text medium" type="text" maxlength="255" value=""/>
<label class="description">Respective Professor</label>
<input name="professor" class="element text medium" type="text" maxlength="255" value=""/>
<label class="description">Position</label>
<select class="element select medium" name="position">
<option value="" selected="selected"></option>
<option value="Student-Bachelors" >Student-Bachelors</option>
<option value="Student-Masters" >Student-Masters</option>
<option value="Student-PhD" >Student-PhD</option>
<option value="Internee" >Internee</option>
<option value="Employee" >Employee</option>
</select>
<label class="description">Duration</label>
<span>
<input name= "duration_start" class="element text" maxlength="255" size="14" value=""/>
<label>Start</label>
</span>
<span>
<input name= "duration_end" class="element text" maxlength="255" size="14" value=""/>
<label>End</label>
</span>
<label class="description">Room & Building</label>
<span>
<input name= "room" class="element text" maxlength="255" size="14" value=""/>
<label>Room</label>
</span>
<span>
<input name= "building" class="element text" maxlength="255" size="14" value=""/>
<label>Building</label>
</span>
<label class="description" >Address </label>
<input name="address" class="element text large" value="" type="text">
<label class="description" >Phone Number </label>
<input name="phone_number" class="element text" maxlength="255" value="" type="text">
<input type="submit" name="submit" id="submit" value="Create my account" title="" border="0">
</form>
<div id="footer"> Login as:
<?php
echo $_SESSION['username'];
?>,
</div>
</div>
<img id="bottom" src="images/bottom.png" alt="">
</body>
</html>
<?php
require_once("db_connect.php");//make connection here
if(isset($_POST['submit']))
{
$name=$_POST['name'];//here getting result from the post array after submitting the form.
$email=$_POST['email'];//same
$department=$_POST['department'];//same
$professor=$_POST['professor'];//same
$position=$_POST['position'];//same
$duration_start=$_POST['duration_start'];//same
$duration_end=$_POST['duration_end'];//same
$room=$_POST['room'];//same
$building=$_POST['building'];//same
$address=$_POST['address'];//same
$phone_number=$_POST['phone_number'];//same
if($name=='')
{
//javascript use for input checking
echo"<script>alert('Please enter the name')</script>";
exit();//this use if first is not work then other will not show
}
if($email=='')
{
echo"<script>alert('Please enter the email')</script>";
exit();
}
if($department=='')
{
echo"<script>alert('Please enter the department')</script>";
exit();
}
if($professor=='')
{
echo"<script>alert('Please enter the professor')</script>";
exit();
}
if($position=='')
{
echo"<script>alert('Please enter the position')</script>";
exit();
}
if($duration_start=='')
{
echo"<script>alert('Please enter the duration end')</script>";
exit();
}
if($duration_end=='')
{
echo"<script>alert('Please enter the duration start')</script>";
exit();
}
if($room=='')
{
echo"<script>alert('Please enter the room')</script>";
exit();
}
if($building=='')
{
echo"<script>alert('Please enter the building')</script>";
exit();
}
if($address=='')
{
echo"<script>alert('Please enter the address')</script>";
exit();
}
if($phone_number=='')
{
echo"<script>alert('Please enter the phone number')</script>";
exit();
}
//here query check weather if user already registered so can't register again.
$check_email_query="select * from new_members WHERE email='$email'";
$run_query=mysqli_query($mysqli,$check_email_query);
if(mysqli_num_rows($run_query)>0)
{
echo "<script>alert('Email $email is already exist in our database, Please try another one!')</script>";
exit();
}
//insert the user into the database.
$insert_user="insert into new_members(name,email,professor,department,position,duration_start,duration_end,room,building,address,phone_number) VALUES ('$name','$email','$professor','$department','$position','$duration_start','$duration_end','$room','$building','$address','$phone_number')";
if(mysqli_query($mysqli,$insert_user))
{
header("Location:manage.php");
exit();
//echo "<script>window.open('manage.php','_self')</script>";
}
}
?>