可捕获的致命错误：类mysqli的对象无法转换为字符串

Question

I was trying to create a Registration form for my project but unfortunately i got this error while i could not find any error in the code!Please help me to get ride from this Issue !

my code

<?php

// this file is connected with regform.php
    $firstname= $_POST['firstname'];
    $lastname =$_POST['lastname'];
    $email =$_POST['email'];
    $password =$_POST['password'];
    $confirmpassword =$_POST['confirmpassword'];
    $address =$_POST['address'];
    $balance =$_POST['balance'];
    $password_hash = md5($password);

$bookConn = mysqli_connect("localhost", "root","", "bookstore") OR die("wrong execution");

    $queryS = "SELECT Email FROM customer";
    $resultSQ = mysqli_query($bookConn , $queryS);
    $flag=0;

while($row=mysqli_fetch_array($resultSQ))
{
    if($email == $row['Email'])
    {
        $flag=1;
    }
}

    if($flag==0)
    {
            if($password == $confirmpassword)

        {
            $query = "INSERT INTO  user (firstName , LastName ,Email , Password , Address , Balance )values('".$firstname."', '".$lastname."' ,'".$email."' , '".$password_hash."', '".$address."' , '".$balance."')";
            $result = mysqli_query($bookConn , $query) OR die($bookConn);

             if ($result)
                {
                    echo "successfuly Registered";
                }

            else {
                    echo "something went wrong!";
                 }
        }

        else{
            echo "Passowrd does not match!";
            }
    }

else{

        echo "Email is already existed in the Database!";

    }
mysqli_close($dbc);
?>

Answer 1

There are two error seems in your code:-

1. mysqli_close($dbc). You never created $dbc in your code. It must be mysqli_close($bookConn).

2. You need to modified your last mysqli_query like this:-

   $result = mysqli_query($bookConn , $query) OR die(mysqli_error($bookConn));

Note:- I hope by doing these changes you will get rid of your proble. Thanks.