Ошибка , некоторые записи введены в базу данных, а некоторые нет

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I am trying to add data to the database only two records entered correctly (first name, member type), and the ID always be 0 
here's the error:

Notice: Undefined index: memberid in C:\xampp\htdocs\...
Notice: Undefined index: lastname in C:\xampp\htdocs\..
Notice: Undefined index: phonenumber in C:\xampp\htdocs\...
Notice: Undefined index: email in C:\xampp\htdocs\...
Notice: Undefined index: username in C:\xampp\htdocs\...
Notice: Undefined index: password in C:\xampp\htdocs\...
Notice: Undefined index: department in C:\xampp\htdocs\...
Records added successfully.

Что я уже пробовал:

вот код.
для HTML

<pre><form action="test.php" method="post">

			<div class="form-group">
				<label for="element-1" class="control-label">First Name</label>
				<input type="text" id="element-1" placeholder="Enter Your First Name Here" class="form-control" , name="firstname">
			</div>
            
             <div class="form-group">
				<label for="element-2" class="control-label">Last Name</label>
				<input type="text" id="element-2" placeholder="Enter Your Last Name Here" class="form-control",name="lastname">
			</div>
            
			<div class="form-group">
				<label for="element-2" class="control-label">Member ID</label>
				<input type="text" id="element-2" placeholder="Enter Your ID Here" class="form-control" ,name="member_id">
			</div>
            
             <div class="form-group">
				<label for="element-2" class="control-label">User Name</label>
				<input type="text" id="element-2" placeholder="Enter Your User Name Here" class="form-control",name="username">
			</div>
            
			<div class="form-group">
				<label for="element-5" class="control-label"> Password</label>
				<input type="password" id="element-5"  placeholder="Enter Your Password Here" class="form-control",name="password">
			</div>
            <div class="form-group">
				<label for="element-5" class="control-label">confirm Password</label>
				<input type="password" id="element-5"  placeholder="confirm Your Password Here" class="form-control",name="confirmpassword">
			</div>
            
            <div class="form-group">
				<label for="element-5" class="control-label"> Email</label>
				<input type="text" id="element-5"  placeholder="Enter Your Email Here" class="form-control",name="email">
			</div>
            
               <div class="tyled-select blue semi-squar">
                   <label for="element-2" class="control-label">Member Type</label>
                    <select name="membertype">
                          <option value="" selected data-default>select member type</option>
                          <option value="professor">Professor</option>
                          <option value="assistent">Assistent</option>
                          <option value="student">Student</option>
                        </select>
            </div>
            
        <div class="form-group">
				<label for="element-2" class="control-label">Phone Number</label>
				<input type="text" id="element-2"  placeholder="Enter Your Phone Number Here" class="form-control",name="phonenumber">
			</div>
            
            <div class="form-group">
				<label for="element-2" class="control-label">department</label>
				<input type="text" id="element-2"  placeholder="Enter Your Department Here" class="form-control",name="department">
			</div>
            
			<button  class="btn btn-primary" type="submit" name="submit">Add</button>

		</form>

а вот и мой php код

if(isset($_POST['submit']))
    {   

// Escape user inputs for security
$id = mysqli_real_escape_string($link, $_REQUEST['member_id']);
$first_name = mysqli_real_escape_string($link, $_REQUEST['firstname']);
$last_name = mysqli_real_escape_string($link, $_REQUEST['lastname']);
$phone= mysqli_real_escape_string($link,$_REQUEST['phonenumber']);
$email=  mysqli_real_escape_string($link,$_REQUEST['email']);
$username=  mysqli_real_escape_string($link,$_REQUEST['username']);
$password=  mysqli_real_escape_string($link,$_REQUEST['password']);
$department=  mysqli_real_escape_string($link,$_REQUEST['department']);


if (isset($_POST['membertype']) ){
   $membertype= $_POST['membertype'];
} 

// attempt insert query execution
$sql = "INSERT INTO `member` (`ID`, `first_name`, `last_name`, `member_type`, `password`, `email`, `phoneNo`, `department`, `user_name`)
VALUES ('$id', '$first_name', '$last_name','$membertype','$password','$email','$phone','$department','$username')";
if(mysqli_query($link, $sql)){
    echo "Records added successfully.";
} else{
    echo "ERROR: Could not able to execute $sql. " . mysqli_error($link);
}
 }

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