$result = mysql_query("SELECT * FROM coupon WHERE Email_Address='$address'");

    if (mysql_num_rows($result)==0){
        echo "ADDING TO DATABASE: " . $address;
        mysql_query("INSERT IN Coupon (Date_Issued, Email_Address, Coupon_Code, Coupon_Expiry) VALUES ('date(Y-m-d)', '$address', '$couponcode', LAST_DAY('date(Y-m-d)');)");
    }