My job is offering an online drawing.  I made a form for the registration that connects to mysql.  The thing is people can only register once.  How can I search the database to find an email and if that email is already entered, tell the person to register on the next drawing?  Any help would be great!

Here is what I came up with.

if($email)
             {
           $query = "SELECT * FROM DrawingOne WHERE email='$email'";
               $result = @mysql_query ($query);
            if (mysql_num_rows($result)==0)
                     {
                   $sqlquery = "INSERT INTO DrawingOne
                       VALUES ('$id','$name', '$co_name','$email','$address','$city','$state','$zip','$bus_phone','$cell_phone','$home_phone' )";
                  $results = mysql_query($sqlquery);
                  mysql_close();
                      echo "Thank you.";
                        exit();
                     }
           }
           else
                {
           echo'<p><font color = "red" size = "+1">Sorry, but that email is already entered into our drawing.  Please enter in our drawing next month.</font></p>';  
            }              

I does not work and I was wondering what I did wrong.