Php mysqli/PDO信息：从mysqli到PDO->；如何处理错误

我已经完成了代码的主要功能，但是我有很多“无用”的代码要删除。
这是一个例子：

else if(isset($_POST['act']) && $_SESSION['status']<3 && $_POST['act']=='delete_ticket'){
    $encid=preg_replace('/\s+/','',$_POST['enc']);
    $encid=($encid!='' && strlen($encid)==87) ? $encid:exit();
    $mysqli = new mysqli($Hostname, $Username, $Password, $DatabaseName);
    $stmt = $mysqli->stmt_init();
    if($stmt){
        $query = "UPDATE ".$SupportTicketsTable." a
                    INNER JOIN ".$SupportUserTable." b
                        ON b.id=a.operator_id
                    SET b.assigned_tickets= CASE  WHEN b.assigned_tickets!='0' THEN (b.assigned_tickets-1) ELSE b.assigned_tickets END  
                WHERE a.enc_id=?";
        if($prepared = $stmt->prepare($query)){
            if($stmt->bind_param('s', $encid)){
                if($stmt->execute()){
                    $query = "DELETE FROM ".$SupportMessagesTable." WHERE `ticket_id`=(SELECT `id` FROM ".$SupportTicketsTable." WHERE `enc_id`=?) ";
                    if($prepared = $stmt->prepare($query)){
                        if($stmt->bind_param('s', $encid)){
                            if($stmt->execute()){
                                $query = "SELECT enc FROM ".$SupportUploadTable." WHERE `ticket_id`=?";
                                if($prepared = $stmt->prepare($query)){
                                    if($stmt->bind_param('s', $encid)){
                                        if($stmt->execute()){
                                            $stmt->store_result();
                                            $result = $stmt->bind_result($mustang);
                                            if($stmt->num_rows>0){
                                                $path='../upload/';
                                                while (mysqli_stmt_fetch($stmt)) {
                                                    if(file_exists($path.$mustang)){
                                                        file_put_contents($path.$mustang,'');
                                                        unlink($path.$mustang);
                                                    }
                                                }
                                            }
                                            $query = "DELETE FROM ".$SupportUploadTable." WHERE `ticket_id`=?";
                                            if($prepared = $stmt->prepare($query)){
                                                if($stmt->bind_param('s', $encid)){
                                                    if($stmt->execute()){
                                                        $query = "DELETE FROM ".$SupportFlagTable." WHERE `enc_id`=?";
                                                        if($prepared = $stmt->prepare($query)){
                                                            if($stmt->bind_param('s', $encid)){
                                                                if($stmt->execute()){
                                                                    $query = "DELETE FROM ".$SupportTicketsTable." WHERE `enc_id`=?";
                                                                    if($prepared = $stmt->prepare($query)){
                                                                        if($stmt->bind_param('s', $encid)){
                                                                            if($stmt->execute()){
                                                                                echo json_encode(array(0=>'Deleted'));
                                                                            }
                                                                            else
                                                                                echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                                                        }
                                                                        else
                                                                            echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                                                    }
                                                                    else
                                                                        echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                                                }
                                                                else
                                                                    echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                                            }
                                                            else
                                                                echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                                        }
                                                        else
                                                            echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                                    }
                                                    else
                                                        echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                                }
                                                else
                                                    echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                            }
                                            else
                                                echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                        }
                                        else
                                            echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                    }
                                    else
                                        echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                                }
                                else
                                    echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                            }
                            else
                                echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                        }
                        else
                            echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                    }
                    else
                        echo json_encode(array(0=>mysqli_stmt_error($stmt)));
                    }
            else
                echo json_encode(array(0=>mysqli_stmt_error($stmt)));
            }
        else
            echo json_encode(array(0=>mysqli_stmt_error($stmt)));
    }
    else
            echo json_encode(array(0=>mysqli_stmt_error($stmt)));
}
else
    echo json_encode(array(0=>mysqli_stmt_error($stmt)));
exit();
}

else if（isset（$\u POST['act']）和&$\u SESSION['status']stmt\u init（）；
如果（$stmt）{
$query=“更新”。$SupportTicketsTable。”a
内部联接“$SupportUserTable.”b
在b.id=a.operator\u id上
设置b.assigned_tickets=当b.assigned_tickets！=“0”时的情况，然后（b.assigned_tickets-1）否则b.assigned_tickets结束
其中a.enc_id=？”；
如果（$prepared=$stmt->prepare（$query））{
if（$stmt->bind_参数（$s'，$encid））{
如果（$stmt->execute（））{
$query=“从“$SupportMessagesTable.”中删除，`ticket\u id`=（从“$SupportTicketsTable.”中选择`id`=”；
如果（$prepared=$stmt->prepare（$query））{
if（$stmt->bind_参数（$s'，$encid））{
如果（$stmt->execute（））{
$query=“从“$SupportUploadTable”中选择enc，其中`ticket\u id`=？”；
如果（$prepared=$stmt->prepare（$query））{
if（$stmt->bind_参数（$s'，$encid））{
如果（$stmt->execute（））{
$stmt->store_result（）；
$result=$stmt->bind_result（$mustang）；
如果（$stmt->num_rows>0）{
$path='../upload/'；
while（mysqli_stmt_fetch（$stmt））{
如果（文件_存在（$path.$mustang））{
文件内容（$path.$mustang，”）；
取消链接（$path.$mustang）；
}
}
}
$query=“从“$SupportUploadTable”中删除，`ticket\u id`=？”；
如果（$prepared=$stmt->prepare（$query））{
if（$stmt->bind_参数（$s'，$encid））{
如果（$stmt->execute（））{
$query=“从“$SupportFlagTable”中删除，其中`enc_id`=？”；
如果（$prepared=$stmt->prepare（$query））{
if（$stmt->bind_参数（$s'，$encid））{
如果（$stmt->execute（））{
$query=“从“$SupportTicketsTable”中删除，`enc_id`=？”；
如果（$prepared=$stmt->prepare（$query））{
if（$stmt->bind_参数（$s'，$encid））{
如果（$stmt->execute（））{
echo json_编码（数组（0=>“已删除”）；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
echo json_编码（数组（0=>mysqli_stmt_error（$stmt））；
}
其他的
回声json
if(statement){

statement or trigger_error($mysqli->error);

$prepared = $stmt->prepare($query) or trigger_error($mysqli->error);

$query = "DELETE FROM ".$SupportMessagesTable." WHERE `ticket_id`=(SELECT `id` FROM ".$SupportTicketsTable." WHERE `enc_id`=?) ";
$db->query($query, $encid);

$query = "UPDATE ".$SupportTicketsTable." a
                INNER JOIN ?n b
                    ON b.id=a.operator_id
                SET b.assigned_tickets= CASE  WHEN b.assigned_tickets!='0' THEN (b.assigned_tickets-1) ELSE b.assigned_tickets END  
            WHERE a.enc_id=?i";
$db->query($query,$SupportUserTable, $encid);
$query = "DELETE FROM ?n WHERE `ticket_id`=(SELECT `id` FROM ?n WHERE `enc_id`=?i) ";
$db->query($query, $SupportUserTable, $SupportTicketsTable, $encid);
$query = "SELECT enc FROM ?n WHERE `ticket_id`=?i";
$mustang = $db->getOne($query, $SupportUserTable, $encid);
if($mustang){