CODEWITHSUNDEEP
phpsql
Shawn31313
Shawn31313

Reputation: 6052

How to check if an IP is in the Database

How do I check if an ip is in the database?

I'm creating a little voting system and right now people can vote more than once.

So i put thier Ip in the database and if its already in the database dont want it to allow the upvote. I get the ips in the database using:

$check = mysql_query("SELECT `ip` FROM `voted`") or die(mysql_error());

I just don't know how to check if the ip that person is voting with is already entered.

Upvotes: 3

Views: 1623

Answers (4)

Anthony Hatzopoulos
Anthony Hatzopoulos

Reputation: 10537

If your going to stick with mysql_* then something like Andrew M advised will work fine. Like he and others suggest though, consider the PDO route (below) if you're just starting to learn PHP

MySQL

<?php
if (!$qry = mysql_query("SELECT COUNT(*) AS `daCount` FROM `voted` WHERE `ip` = '".mysql_escape_string($_SERVER['REMOTE_ADDR'])."'")) {
    die('Whamm PoW! Oops, we made a boo boo!');
}

list($check) = mysql_fetch_row($qry);
if ($check > 0) {
    echo 'Thanks but you already voted!';
}
else {
    echo 'Please make your vote: Yes or No?';
}

PDO

<?php
try { // to connect to database
    $db = new PDO('mysql:host=localhost;dbname=testdb;charset=UTF-8', 'username', 'password', array(
        PDO::ATTR_EMULATE_PREPARES => false,
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
    ));
} catch (PDOException $e) {
    die('Bazinga! Oops, we made a boo boo!');
}

try { // to execute query and stuff
    $stmt = $db->prepare('SELECT `ip` FROM `voted` WHERE `ip`=?');
    $stmt->execute(array($_SERVER['REMOTE_ADDR']));
    $row_count = $stmt->rowCount();
    if ($row_count > 0) {
        echo 'Thanks but you already voted!';
    }
    else {
        echo 'Please make your vote: Yes or No?';
    }

} catch(PDOException $e) {
    die('Kaboom! Oops, we made a boo boo!');
}

Upvotes: 0

Andrew M
Andrew M

Reputation: 4288

Take a look at the WHERE clause in MySQL:

http://www.tizag.com/mysqlTutorial/mysqlwhere.php

$ip = mysql_real_escape_string([the IP address]);
$q = mysql_query("SELECT `ip` FROM `voted` WHERE `ip`= '$ip'");
if(mysql_num_rows($q) > 0){
    // They already are in the database
}

Remember-- sanitize your inputs. Personally, I would use parameters and bindings, but if you are going plain-vanilla MySQL then just use the escaping function. But remember, the mysql_ functions are being deprecated, so I would avoid them if possible. (See PDO)

Upvotes: 2

Andrea Girardi
Andrea Girardi

Reputation: 4427

I should use something like:

SELECT count(*) INTO counter from `voted` WHERE ip = '0.0.0.0'

and in your php code you'll check if counter is more than 0.

Upvotes: 0

mellamokb
mellamokb

Reputation: 56769

I assume you already have a way to get the IP address (since you're inserting them into the database). So it's a matter of a WHERE clause to validate:

$check = mysql_query("SELECT `ip` FROM `voted` WHERE `ip` = '$theIP'")...

Then check if you get any results back. If you do, then refuse the vote.

Note, however, that validating entirely based on IP addresses will give you a lot of false negatives.

Upvotes: 2

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