Please modify my script to the prepared statement

[aetareq]

I've developed a php script to connect to the mysql, get and store some info of the users. I've heard to write the php in prepared statement to prevent sql injection hacking. I'm quite unfamiliar with this term. So anyone can help me modifying my scripts in procedural prepared statement would be really so much appreciated. here's my code:

<?php
$ipaddress = '';
    if (getenv('HTTP_CLIENT_IP'))
        $ipaddress = getenv('HTTP_CLIENT_IP');
    else if(getenv('HTTP_X_FORWARDED_FOR'))
        $ipaddress = getenv('HTTP_X_FORWARDED_FOR');
    else if(getenv('HTTP_X_FORWARDED'))
        $ipaddress = getenv('HTTP_X_FORWARDED');
    else if(getenv('HTTP_FORWARDED_FOR'))
        $ipaddress = getenv('HTTP_FORWARDED_FOR');
    else if(getenv('HTTP_FORWARDED'))
        $ipaddress = getenv('HTTP_FORWARDED');
    else if(getenv('REMOTE_ADDR'))
        $ipaddress = getenv('REMOTE_ADDR');
    else
        $ipaddress = 'UNKNOWN';
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "db_test";
$con = mysqli_connect($servername, $username, $password, $dbname);
$sql = "SELECT time FROM userinfo WHERE ipaddress='$ipaddress'";
$result = mysqli_query($con, $sql);
if (mysqli_num_rows($result) > 0) {
    $row = mysqli_fetch_array($result);
    $rectime = $row['time'];
    $curtime = date("Y-m-d H:i:s");
    $diff = round((strtotime($curtime) - strtotime($rectime))/(60*60));
    if ($diff > 0) {
        $sqli = "INSERT INTO userinfo (id, ipaddress, time) VALUES ('', '$ipaddress', NOW()) ON DUPLICATE KEY UPDATE time = NOW();";
        mysqli_multi_query($con, $sqli);
        echo "welcome again";
    } else {
        echo "welcome";
    }
} else {
    $sqli = "INSERT INTO userinfo (id, ipaddress, time) VALUES ('', '$ipaddress', NOW());";
    mysqli_multi_query($con, $sqli);
    echo "welcome";
}
mysqli_close($con);
?>

[maxxd]

Best place to start is always the manual - http://php.net/manual/en/mysqli.prepare.php

 

Basically, you write your SQL, use the mysqli interface to prepare it, then bind the parameters to the placeholders in the query, then run the query. Personally, I've always found PDO easier to deal with for this, so you may want to check that out as well.