Send email to DB

[helmz]

Im having some problems trying to send mail to db, and the if arent correct... but im new and i dont have too much idea need some help please, first there are legal conditions to accept, then a email filter, and then must know if mail is in database already.

This is the code:

<?php

$email = $_POST["email"];

// $search = "SELECT * FROM `[db]` WHERE `email` = '$email'";
// $result = mysql_query($search) or die ('Error');
// $num = mysql_num_rows($result);

if (isset($_POST['privacidad']))
{   $privacidad = '1';
    echo"Terms accepted.";}

    if ($seleccionado == '1') {

        // Comprobar si el usuario introducido existe
                  $error.=  "Check again:<br /><br />";
                  $checkuser = mysql_query("SELECT email FROM email WHERE email='$email'");
                  $username_exist = mysql_num_rows($checkuser);

                  if($username_exist > 0){

                  $error.= "- Already exists<br />";

                  }

        //if(!$email == "" && (!strstr($email,"@") || !strstr($email,"."))) {

        //Check mail
                if(eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email)) {  echo "";

                } else {

                echo "- Incorrect email. ";}
                }

                //$estat = "<h2>Not sent</h2>";
                //echo $estat;
                //die ("Go back!");

        } else {

               // if ($num != 0) {
               // echo ("Email used"); }
               // else {

                mysql_connect('host' , 'user', 'pw');
                mysql_select_db("dbname");
                mysql_query("INSERT INTO email (email) VALUES ('$email')");

                    echo mysql_error();
                    echo 'email sent 222';
                    echo $email;
                }

 
    } else {
        echo 'must accept legal terms';
        alert ('must accept legal terms');

    }

There are some comments that are previosly tryies, sorry about. Must say CONNECTING WITH DB IS NOT THE PROBLEM(I tryed it before putting some ifs), the problem is syntax i think... thanks