mysqli论坛第二个声明

Question

First of all, sorry for my bad English (I used google translate). I already read many forums but I can not find the answer. I only know that the error is in mysqli_stmt_execute ($ stmt2) ;. I would like to keep it in Procedural style.

if(isset($_GET['subject'])){
            echo"<table>";
            $stmt = mysqli_prepare($mysqli,"SELECT * FROM `***`.`topics` WHERE categorie = ?");
            $stmt2 = mysqli_prepare($mysqli,"SELECT username FROM `***`.`users` WHERE id = ?");
            //pakketje maaken
            mysqli_stmt_bind_param($stmt, 'i' , $_GET['subject']);
            mysqli_stmt_bind_param($stmt2, 'i' , $by);
            //uitvoeren
            mysqli_stmt_execute($stmt);
            //resultaat naar php variablen
            mysqli_stmt_bind_result($stmt, $id , $question , $categorie , $by , $date);
            while (mysqli_stmt_fetch($stmt)) {
            mysqli_stmt_execute($stmt2);
            mysqli_stmt_bind_result($stmt2, $bb);
            echo'<tr><td>
        <fieldset id="'.$id.'" onClick="types(this.id)">
        <table class="forumposts">
            <tr><td><b>'.$question.'</b></td><td>'.$bb.'</td><td>'.$date.'</td></tr>
        </table>
        </fieldset></td></tr>';}
            mysqli_stmt_close($stmt2);
            mysqli_stmt_close($stmt);
                echo'</table><script>
            function types(clicked_id){
                var c = clicked_id;
                window.location.href = "http://www.***.be/forum/index.php?subject='.$categorie.'&question="+c;  
            }
            </script>';