SQL first entry not adding to database - php

Question

Could someone please help with the code below. I am trying to create a registration query, however when it is submitted, I get an error for the following line:
$insert_query = "insert into members (First_name, last_name, Address_1, Address_2, Postcode, Email, Membership_Number, Password) values('$fname','$lname','$address1','$address2','$postcode','$email','$member','$password')";
This is only affecting the first_name, as the other field names are successfully submitted.
Your help would be much appreciated!!
<?php
$con = mysql_connect("localhost","root","") or die(mysql_error());
$select_db = mysql_select_db("thistlehc",$con);
if(isset($_POST['register']))
$fname = mysql_real_escape_string($_POST['fname']);
$lname = mysql_real_escape_string($_POST['lname']);
$address1 = mysql_real_escape_string($_POST['address1']);
$address2 = mysql_real_escape_string($_POST['address2']);
$postcode = mysql_real_escape_string($_POST['postcode']);
$email = mysql_real_escape_string($_POST['email']);
$member = mysql_real_escape_string($_POST['member']);
$password = mysql_real_escape_string($_POST['password']);
$query = "select membership_number from members where membership_number='$member'";
$link = mysql_query($query)or die(mysql_error());
$num = mysql_num_rows($link);
if ($num>0){
echo 'Membership Number already exists'; //Membership number already taken
}
else {
$insert_query = "insert into members (First_name, last_name, Address_1, Address_2, Postcode, Email, Membership_Number, Password) values('$fname','$lname','$address1','$address2','$postcode','$email','$member','$password')";
$result = mysql_query($insert_query)or die(mysql_error());
echo "Registered Successfully!";
}
?>

Answer 1

Look's to me like you forgot to encapsulate the contents of your if statement.
if(isset($_POST['register']))
Because it doesn't have curly brackets around the code to be executed, only the first line immediately after is executed. In your case, the if statement seemingly returned false, and the line defining $fname was not executed, hence an undefined variable.
You want to use something similar to this -
if(isset($_POST['register'])){
$fname = mysql_real_escape_string($_POST['fname']);
$lname = mysql_real_escape_string($_POST['lname']);
$address1 = mysql_real_escape_string($_POST['address1']);
...
}