User.php

<?php
include_once('DbConnection.php');
 
class User extends DbConnection{

    public function __construct(){

        parent::__construct();
    }
    
    public function check_login($username, $password){

        $sql = "SELECT * FROM users WHERE username = '$username' AND password = '".md5($password)."'";
        
        $query = $this->connection->query($sql);

        if($query->num_rows > 0){
            $row = $query->fetch_array();
            return $row;
        }
        else{
            return false;
        }
    }

    public function insert($name, $username, $password){

        $sql = "INSERT into users (fname, username, password) VALUES('$name', '$username', '".md5($password)."')";
       
        $query = $this->connection->query($sql);

        if($query){
            return true;
        }
        else{
            return false;
        }
    }
        
    public function details($sql){

        $query = $this->connection->query($sql);
        
        $row = $query->fetch_array();
            
        return $row;       
    }
    
    public function escape_string($value){
        
        return $this->connection->real_escape_string($value);
    }
}