isset in php not working - php

Question

I have a to get a data from this form and insert it into database.
I am not able to find any solution online.
Everything works on the browser but the data is not getting stored into the table and echo inside the if block is not printed on screen.
The code is what can be seen below.
HTML
<form action="" method="POST">
<div class="container-fluid">
<div class="container">
<div class="row">
</div>
<div class="row">
<div class="col-xs-12 col-sm-6 col-md-10 col-lg-4 col-md-offset-3" style="top:100px">
<div class="offer offer-radius offer-primary">
<div class="shape">
<div class="shape-text">
<span class="glyphicon glyphicon-user"></span>
</div>
</div>
<div class="offer-content">
<h4 style="margin-left:70px;font-size:20px">Enter your details below and enroll your slot</h4>
<div class="container col-xs-12">
<div class="stepwizard">
<div class="stepwizard-row setup-panel">
<div class="stepwizard-step">
<a href="#step-1" type="button" class="btn btn-primary btn-circle">
<i class="glyphicon glyphicon-user" style="margin-left: -18px;top: -24px;font-size: 90%;"></i></a>
</div>
<div class="stepwizard-step">
<a href="#step-2" type="button" class="btn btn-default btn-circle" disabled="disabled">
<i class="glyphicon glyphicon-education" style="margin-left: -18px;top: -24px;font-size: 90%;"></i></a>
</div>
<div class="stepwizard-step">
<a href="#step-4" type="button" class="btn btn-default btn-circle" disabled="disabled">
<i class="glyphicon glyphicon-ok" style="margin-left: -18px;top: -24px;font-size: 90%;"></i></a>
</div>
</div>
</div>
<div class="row setup-content" id="step-2">
<div class="col-xs-12">
<div class="col-md-10">
<h3>Qualification</h3>
<div class="col-xs-12 col-xs-offset-1" style="top:-50px">
<button class="btn btn-primary nextBtn btn-lg pull-right" type="button" >Next</button>
</div>
<div class="col-xs-12" style="clear:both;top:-45px">
<input maxlength="20" type="text" required="required" class="form-control" placeholder="B Tech" readonly="" />
</div>
<div class="col-xs-12 form-group" style="clear:both;top:-40px">
<label for="subject">
Year of Pass out</label>
<input maxlength="20" type="text" required="required" class="form-control" placeholder="2016" readonly="" />
</div>
<div class="col-xs-12 form-group" style="clear:both;top:-40px">
<label for="subject">
Branch</label>
<select id="subject" name="subject" class="form-control" required="required">
<option value="na" selected="">Choose One:</option>
<option value="service">Computer Science</option>
<option value="suggestions">Information Technology</option>
<option value="product">Electronics & Communication</option>
<option value="product">Electronics & Electrical</option>
<option value="product">Instrumentation</option>
</select>
</div>
<div class="col-xs-12" style="clear:both;top:-40px">
<label for="subject">
Percentage (%)</label>
<input maxlength="6" type="text" class="form-control" placeholder="Your Percentage" name="percentage" />
</div>
</div>
</div>
</div>
</div>
<div class="row setup-content" id="step-1">
<div class="col-xs-12">
<div class="col-md-12">
<div class="container">
<div class="row">
<div class="col-xs-4">
<button class="btn btn-primary nextBtn btn-lg pull-right" type="button" >Next</button>
<h3>Personal Information</h3>
<div class="col-xs-12" style="padding:15px">
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-user fa" aria-hidden="true"></i></span>
<input maxlength="100" type="text" class="form-control" placeholder="First Name" name="F_Name" />
</div>
</div>
<div class="col-xs-12" style="clear:both;padding:10px">
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-user fa" aria-hidden="true"></i></span>
<input maxlength="100" type="text" class="form-control" placeholder="Last Name" name="L_Name" />
</div>
</div>
<div class="col-xs-12" style="clear:both;padding:10px">
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-envelope fa" aria-hidden="true"></i></span>
<input maxlength="100" type="text" class="form-control" placeholder="Your Email" name="EmailID" />
</div>
</div>
<div class="col-xs-12" style="clear:both;padding:10px">
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-phone fa" aria-hidden="true"></i></span>
<input maxlength="14" type="text" class="form-control" placeholder="([phone]" name="Phone_Number" />
</div>
</div>
<div class="col-xs-12" style="clear:both;padding:10px">
<div class="input-group">
<span class="input-group-addon"><i class="fa fa-phone fa" aria-hidden="true"></i></span>
<input maxlength="14" type="text" class="form-control" placeholder="Reference Code" name="R_Code" />
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="row setup-content" id="step-4">
<div class="col-xs-12">
<div class="col-xs-12">
<div class="container" style="height:307px;">
<h4>Registered</h4>
<div class="col-xs-4" style="margin-left:-60px;top:60px">
<button class="btn btn-success completeBtn btn-lg pull-right" type="button" name="proceed">Proceed to payment</button>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</form>
PHP
<?php
$cn= mysqli_connect('localhost','testuser','password','invoicedb');
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
echo "string";
if(isset($_POST["proceed"]))
{echo "string";
$fname=$_POST['F_Name'];
$lname=$_POST['L_Name'];
$emailID=$_POST['EmailID'];
$phone_number=$_POST['Phone_Number'];
$reference_code=$_POST[‘R_Code’];
$branch=$_POST[‘subject’];
$percentage=$_POST[‘percentage’];
echo "insert into students(first_name,last_name,email,phone_number,reference_code,branch,percentage) VALUES ('$fname','$lname','$emailID','$phone_number','$reference_code','$branch','$percentage')";
mysqli_query($cn,"insert into students(first_name,last_name,email,phone_number,reference_code,branch,percentage) VALUES ('$fname','$lname','$emailID','$phone_number','$reference_code','$branch','$percentage')");
//best outside the if statement so user isn't stuck on a white blank page.
header("location:confirm.php");
exit;
}
?>

Answer 1

You can access $_POST[] values only if your form is submitted,
So, Replace this,
<button class="btn btn-success completeBtn btn-lg pull-right" type="button" name="proceed">Proceed to payment</button>
with This,
<button class="btn btn-success completeBtn btn-lg pull-right" type="submit" name="proceed">Proceed to payment</button>
It will work, without replacing your button with input.

Answer 2

If you are submitting the form in the same page then you should use -
<?php
$cn= mysqli_connect('localhost','testuser','password','invoicedb');
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
echo "string";
if($_SERVER["REQUEST_METHOD"] == "POST")
{echo "string";
$fname=$_POST['F_Name'];
$lname=$_POST['L_Name'];
$emailID=$_POST['EmailID'];
$phone_number=$_POST['Phone_Number'];
$reference_code=$_POST[‘R_Code’];
$branch=$_POST[‘subject’];
$percentage=$_POST[‘percentage’];
echo "insert into students(first_name,last_name,email,phone_number,reference_code,branch,percentage) VALUES ('$fname','$lname','$emailID','$phone_number','$reference_code','$branch','$percentage')";
mysqli_query($cn,"insert into students(first_name,last_name,email,phone_number,reference_code,branch,percentage) VALUES ('$fname','$lname','$emailID','$phone_number','$reference_code','$branch','$percentage')");
//best outside the if statement so user isn't stuck on a white blank page.
header("location:confirm.php");
exit;
}
?>

Answer 3

if(isset($_POST["proceed"])){}
$_POST["proceed"] is not set at all, it needs a value in it to make sure it is set.
instead of checking if, just print the post values and try if your form is getting submitted.
inside php tag write below code and try echoing the data.
echo '<pre>';
print_r($_POST);
echo '----------------';
print_r($_REQUEST);