Check if two textbox value is same in php - php

Question

I've created a add user page where users can be added to the database, the code is below i would want to compare two textbox and if they are matching(password=conform password) then it should be inserted in the database , how can i achieve that in php
<?php
require("../connect.php");
error_reporting(0);
/*
if(!(adminsessioncheck()))
header('location:index.php'); */
if(isset($_POST['add']))
{
$username=$_POST['username'];
$password=$_POST['password'];
mysql_query("INSERT INTO user VALUES('','$username','$password')") or die(mysql_error());
}
?>
<div style=" width:250px; margin-left:auto; margin-right:auto;">
<div class="heading1" style="text-align:center">Add a new User</div>
<br>
<form action="" method="post" onsubmit="msgbox()">
<table width="330" height="135" border="0" class="text">
<tr>
<td><label>User Name</label></td>
<td><input type="text" name="username" id="username" required></td>
</tr>
<tr>
<td><label>Password</label></td>
<td><input type="password" id="password" name="password" required></td>
</tr>
<tr>
<td><label>Confirm Password</label></td>
<td><input type="password" id="cpassword" name="cpassword" required></td>
</tr>
<tr><td></td></tr>
<tr><td></td></tr>
<tr><td></td><td align="center"><input type="submit" name="add" value="Add"></td></tr>
</table>
</form>
</div>
</div>

Answer 1

Simple.
if($_POST['password'] !== $_POST['cpassword']) {
header("location:index.php")
} else {
mysql_query("INSERT INTO user VALUES('','$username','$password')") or die(mysql_error());
}

Answer 2

To only check after post you can do this.
if(isset($_POST['add']))
{
$username=mysql_real_escape_string($_POST['username']);
$password=mysql_real_escape_string($_POST['password']);
if($_POST['password'] == $_POST['cpassword'])
mysql_query("INSERT INTO user VALUES('','$username','$password')") or die(mysql_error());
else
//create error message
}
But it would be better to check before posting. Also NEVER insert unsanitized data into your database! ever! Plus others will tell you so i might as well mention mysql is deprecated, check out mysqli instead.

Answer 3

if(isset($_POST['add']))
{
$username=$_POST['username'];
$password=$_POST['password'];
if ($_POST['password']!= $_POST['cpassword'])
{
echo("Password did not match! Try again. ");
}
else
{
mysql_query("INSERT INTO user VALUES('','$username','$password')") or die(mysql_error());
}
}