classes db.php

<?php
    class DB{
        private static $_instance = null;
        private $_pdo,
                $_query,
                $_error=false,
                $_results,
                $_count=0;

        public function __construct(){
            try{
                $this->_pdo = new PDO('mysql:host=localhost;dbname=wakamegroup','root','');
                //echo "connected";
            }catch(PDOException $e){
                die($e->getMessege());
            }
        }

        public static function getInstance(){
            if(!isset(self::$_instance)){
                self::$_instance = new DB();
            }
        return self::$_instance;
        }

        public function query($sql, $params = array()){
            $this->_error = false;
            if($this->_query = $this->_pdo->prepare($sql)){
                $x = 1;
                if(count($params)){
                    foreach($params as $param){
                        $this->_query->bindValue($x, $param);
                        $x++;
                    }
                }
                if($this->_query->execute()){
                    $this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
                    $this->_count = $this->_query->rowCount();
                }
                else{
                    $this->_error =  false;
                }
            }
            return $this;
        }

        private function action($action, $table, $where=array()){
            if(count($where)===3){
                $operators = array('=','>','<','<=','>=');

                $field = $where[0];
                $operator = $where[1];
                $value = $where[2];

                if(in_array($operator, $operators)){
                    $sql = "{$action} FROM {$table} WHERE {$field} {$operator} ?";
                    if(!$this->query($sql,array($value))->error()){
                        return $this;

                    }
                }
            }
            return false;
        }

        public function get($table, $where){
            return $this->action('SELECT *', $table, $where);
        }

        public function delete($table, $where){
            return $this->action('DELETE *', $table, $where);
        }

        public function insert($table, $fields = array()){
           
                $keys = array_keys($fields);
                $values = '';
                $x = 1;

                foreach($fields as $field){
                    $values .= '?';
                    if($x < count($fields)){
                        $values .= ', ';
                    }

                    $x++;
                }
                

                $sql = "INSERT INTO users " . "(`" . implode('` , `' , $keys) . "`) VALUES ({$values})";

                if(!$this->query($sql, $fields)->error()){
                    return true;
                }
            
            return false;
        }

        public function update($table, $id, $fields){
            $set = '';
            $x = 1;

            foreach($fields as $name => $value){
                $set .= "{$name} = ?";
                if($x < count($fields)){
                    $set .= ', ';
                }
                $x++;
            }


            $sql = "UPDATE {$table} SET {$set} WHERE id = {$id}";
            
            if(!$this->query($sql,$fields)->error()){
                return true;
            }
            return false;

        }

        public function results(){
            return $this->_results;
        }

        public function first(){
            return $this->results()[0];
        }

        public function error(){
            return $this->_error;
        }

        public function count(){
            return $this->_count;
        }

}
?>