我在PHP中创建了测验，但是在注册数据库中没有更新

Question

I created PHP quiz for my website In this quiz when I signup echo running signup successfully and no error comes but data not updating in database. When I entered value manually in database table I successfully loged in so how can I update data in database through signup form. I uploded this in my website http://www.kpsclasses.com/quiz/index.php

This is my users.php

<?php session_start(); class users{
public $host="localhost:3306";
public $username="root";
public $pass="";
public $db_name="";
public $conn;
public $data;
public $cat;
public $qus;

public function __construct()
{
    $this->conn=new mysqli($this->host,$this->username,$this->pass,$this->db_name);
    if($this->conn->connect_errno)
    {
        die ("database connection failed".$this->conn->connect_errno);
    }
}

public function signup($data)
{
    $this->conn->query($data);
    return true;
}

public function signin($name,$KPS)
{
    $query=$this->conn->query("select name,KPS from signup where name='$name' and KPS='$KPS'");
    $query->fetch_array(MYSQLI_ASSOC);
    if($query->num_rows>0)
    {
        $_SESSION[ 'display_home.php' ] = TRUE;
        $_SESSION['name']=$name;
        return true;
    }
    else
    {
        return false;
    }

}
public function users_profile($name)
{
    $query=$this->conn->query("select * from signup where name='$name'");
    $row=$query->fetch_array(MYSQLI_ASSOC);
    if($query->num_rows>0)
    {
        $this->data[]=$row;
    }
    return $this->data;
}
public function cat_shows()
{       
    $query=$this->conn->query("select * from category");
   while($row=$query->fetch_array(MYSQLI_ASSOC))        
    {

        $this->cat[]=$row;
    }
    return $this->cat;

}
public function qus_show($qus)
{
    //echo $qus;
     $query=$this->conn->query("select * from questions where cat_id='$qus'");
    while($row=$query->fetch_array(MYSQLI_ASSOC))       
    {           
        $this->qus[]=$row;
    }
    return $this->qus; 
}
public function answer($data)
{
     $ans=implode("",$data);
     $right=0;
     $wrong=0;
     $no_answer=0;
     $query=$this->conn->query("select id,ans from questions where cat_id='".$_SESSION['cat']."'");
    while($qust=$query->fetch_array(MYSQLI_ASSOC))      
    {           
        if($qust['ans']==$_POST[$qust['id']])
        {
             $right++;
        }
        elseif($_POST[$qust['id']]=="no_attempt")
        {
             $no_answer++;
        }
        else
        {
            $wrong++;
        }
    }
    $array=array();
    $array['right']=$right;
    $array['wrong']=$wrong;
    $array['no_answer']=$no_answer;
    return $array;

}
public function add_quiz($rec)
{
    $a=$this->conn->query($rec);
    return true;
} public function url($url)
{
    header("location:".$url);
} } ?>    

signup_sub.php

<?php
include("class/users.php");
$register=new users;
extract($_POST);
$img_name=$_FILES['img']['name'];
$tmp_name=$_FILES['img']['tmp_name'];
move_uploaded_file($tmp_name,"img/".$img_name);
$query="insert into signup values ('','$n','$e','$p','$k','$img_name')";
if($register->signup($query))
{
    $register->url("index.php?run=success");
}


?>

Answer 1

In signup values I updated id null because it is auto increamnet in database table

$query="insert into signup values (NULL,'$n','$e','$p','$k','$img_name')";