mysqli_affected_rows in PHP insert

Question

I have this code:

if(mail($to, $subject, $message, $headers)){
    $insert_member_sql = \"INSERT INTO members (id, username) VALUES(\'$id\', \'$username\')\"         


        

Answer 1

if(mail($to, $subject, $message, $headers)){
    $insert_member_sql = "INSERT INTO members (id, username) VALUES('$id', '$username')";

    if (!mysql_query($insert_member_sql) ){
    echo "1";
    }else{
    echo "0";
    }
};