PHP VIEIRA 3

<!DOCTYPE html>
<html>
<head>
    <title>Exemplo</title>
    <style type="text/css">
        #ger1{
            margin: auto;
            background-color: #993333;
            color: white;
            width: 500px;
            height: auto;
            border:2px solid black;
            border-radius: 10px;
        }
        .ger2{
            margin: auto;
            background-color: #993333;
            color: white;
            width: 500px;
            height: auto;
            border:2px solid black;
            border-radius: 10px;
        }
        p{
            text-align: center;
        }

        .alerta{
            border-radius: 10px;
            text-align: center;
            margin: auto;
            background-color: red;
            margin-right: 20px;
            margin-left: 20px;
        }
        .done{
            border-radius: 10px;
            text-align: center;
            margin: auto;
            background-color: green;
            margin-right: 20px;
            margin-left: 20px;
        }
        .tabelanova{
            margin: auto;
        }
    </style>
</head>
<body>
    <?php
        $bd_host="localhost";
        $bd_user="root";
        $bd_password="";
        $bd_database="13787_3";
        $msg= "";
        $existe="";
        $numero=$idade=$email=$local="";
        $mq = new mysqli($bd_host,$bd_user,$bd_password,$bd_database);


        if(isset($_POST["submit"])){
            //if($_POST["Idade"]!='' && ...)
            $qr = "INSERT INTO tbl_13787(Numero,Idade,Email,Local) VALUES(?,?,?,?)";
            $st = $mq->prepare($qr);
            $st->bind_param('iiss', $_POST["Numero"],
                                    $_POST["Idade"],
                                    $_POST["Email"],
                                    $_POST["Local"]);

        if ($st->execute() && $st->affected_rows>0){
            $msg= "<p class='done'>Foi inserido/atualizado um registo!</p>";

        }
        else{
                $msg='<p class="alerta"> Erro: ('. $mq->errno .') '. $mq->error .'</p>';
                $erro=1;
            }

        $st->close();


        }
        if(isset($_POST["Consultar"])){
            $qr="SELECT * FROM tbl_13787 ORDER BY Numero";

            $results = $mq->query($qr);
            echo "<table class=tabelanova border='1'>";
            echo "<td>Numero</td>";
            echo "<td>Idade</td>";
            echo "<td>Email</td>";
            echo "<td>Local</td>";
                while ($row = $results->fetch_assoc()) {
                    echo "<tr>";
                    echo "<td>".$row["Numero"]."</td>";
                    echo "<td>".$row["Idade"]."</td>";
                    echo "<td>".$row["Email"]."</td>";
                    echo "<td>".$row["Local"]."</td>";
                    echo "</tr>";
                }
            echo "</table>";
        }
        else{

            if(isset($_POST["pesquisar"])){

                $qr="SELECT * FROM tbl_13787 where Numero=?";
                $st=$mq->prepare($qr);
                $st->bind_param('i', $_POST["Numero"]);
                $st->execute();
                $st->bind_result($numero,$idade,$email,$local);
                if($st->fetch()){
                    $existe=true;
                    $msg='<p class="done" > Registo Encontrado</p>';

                }
                else{
                    $existe=false;
                    $msg='<p class="alerta">Registo nao Encontrado</p>';
                }
                $st->close();
            }
            else{
                if(isset($_POST["Alterar"])){
                    $qr="UPDATE tbl_13787 SET Idade=?, Email=?, Local=? WHERE Numero=?";
                    $st=$mq->prepare($qr);
                    $st->bind_param('issi',$_POST["Idade"],$_POST["Email"],$_POST["Local"],$_POST["Numero"]);
                    $st->execute();
                    $st->close();
                }
                else{
                    if(isset($_POST["Apagar"])){
                        $qr="DELETE FROM tbl_13787 WHERE Numero= ?";
                        $st=$mq->prepare($qr);
                        $st->bind_param('i',$_POST["Numero"]);
                        $st->execute();
                        $st->close();
                    }
                }
            }
        }


    ?>
            <br>
            <form method="post" action="" id="tbl" class=ger2 name="tbl">
                <input type="hidden" name="pesquisar" value="1"/>
            <p>Seleciona: <select name="Numero" id="Numero" onChange="document.tbl.submit();">
                <option value="-1">
                    Selecione um registo
                </option>
                    <?php
                    $qrs="SELECT * FROM tbl_13787";
                $st = $mq->query($qrs);
                    $option = '';
                while($row = $st->fetch_assoc())
                        {
                    echo '<option value = "'.$row['Numero'].'">'.$row['Numero'].'</option>';
                    }
                    $st->close();
                    ?>
            </select>
        </form>
            <form method="post" action="" id="ger1" class="ger2">
            <p>Numero:<input type="number" name="Numero" value="<?php echo $numero ?>"><input type="submit" name="pesquisar" value="Pesquisar registo"></p>
            <p>Idade:<input type="number" name="Idade" value="<?php echo $idade ?>"></p>
            <p>Email:<input type="text" name="Email" value="<?php echo $email ?>"></p>
            <p>Local:<input type="text" name="Local" value="<?php echo $local ?>"></p>
            <p><input type="submit" name="submit" value="Inserir registo" id="botao1"></p>
            <p><input type="submit" name="Consultar" value="Consultar registo" id="botao2"></p>
            <?php if ($existe==true) {?>
                <p><input type="submit" name="Alterar" value="Alterar registo" /></p>
                <p><input type="submit" name="Apagar" value="Eliminar registo" /></p>
            <?php }?>
            <p>
                <?php
                    echo $msg;
                    $mq->close();
                ?>
            </p>
        </form>
     </body>
</html>