Facing issue while running PHP script - php

Question

I have a form in HTML which posts two values hostname and ip_address.
<form action="demo-select.php" method="post" />
<p>HOSTNAME/IPADDRESS: <input type="text" name="HOSTNAME" name="IP_ADDRESS" /></p>
<input type="submit" value="Submit" />
</form>
If I enter the hostname/ip_address and submit it, it will take me to demo-select.php script.
In demo-select.php script I'm able to get the output for hostname from my MySQL db. How should I get the output based on ip_address?
$value = $_POST['HOSTNAME'];
$query = "SELECT * FROM <tablename> WHERE HOSTNAME='$value'";
$result = mysql_query($query);
This script connects to a MySQL db and gets the output based on the hostname. What modifications should I make to get the output based on ip_address as well?
Table columns:
HOSTNAME
IP_ADDRESS
cpus
MEMORY

Answer 1

HTML:
You can't assign two names to an HTML element. I'd suggest that you either use two fields or use a dropdown / radio button along with the form field for the user to specify whether they're entering a hostname or an ip_address:
<form action="demo-select.php" method="post" />
<select name="address_type">
<option value="ip"> IP Address </option>
<option value="host"> Host Name </option>
</select>
<input type="text" name="host_name_or_address" />
<input type="submit" value="Submit" />
</form>
An assumption here is that you'd want the user to enter as input only one of hostname or ip_address in a single submit. If you want both to be relayed to the PHP at once, then please get rid of the select dropdown and use two input fields instead.
PHP:
Check what's been received in address_type and determine what query to use accordingly:
$address_type = $_POST['address_type'];
$value = $_POST['host_name_or_address'];
if($address_type == "host"){
// If looking for partial matches, use... WHERE HOSTNAME LIKE '%$value'
$sql = "SELECT * FROM <tablename> WHERE HOSTNAME = '$value' ";
}
else{
$sql = "SELECT * FROM <tablename> WHERE IP_ADDRESS = '$value' ";
}
Again, if you want both fields to be searched for at once, then along with the HTML edits indicated in the narration above, you'll have to receive in a PHP variable the value of the second input field too. Also then please get rid of the if-else construct here above and write a single, combined query as:
$sql = "SELECT * FROM <tablename> WHERE HOSTNAME = '$value1' AND IP_ADDRESS = '$value2' ";
Finally, please don't use mysql_*() functions in any PHP code. They're long deprecated and are very vulnerable to SQL Injection Attacks as Daniel has already suggested in his answer. Please have a look at MySQLi and PDO Prepared Statements instead. These utilities provide a cleaner way to write your queries and also a much safer mechanism to shield them against potential risks.