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PHP

Posted by Ashish Mehra
Ashish Mehra
Courses Plus Student 3,575 Points

execute() return false

Hey I am practicing login system with oop from codecourse https://www.youtube.com/watch?v=PaBWDOBFxDc&list=PLfdtiltiRHWF5Rhuk7k4UAU1_yLAZzhWc&index=8 . Till the database connectivity everything moving in right direction but when i try to run query execution return false.

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

    private function __construct(){
        try{
          $this->_pdo = new PDO(
            "mysql:".Config::get("mysql/host").";
            dbname=".Config::get("mysql/db").";
            port=".Config::get("mysql/port")."\",\""
            .Config::get("mysql/username")."\",\""
            .Config::get("mysql/password")."\"");
        }catch(Exception $e){
           echo $e->getMessage();
           exit();
        }
    }

    public static function get_instance(){
        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()){   //here i m geeting value as false
            echo "success";
              $this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ); 
              $this->_count = $this->_query->rowCount();
           }else{
            echo "error";
             $this->_error = true;
           }
        }
    }

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

  }

//index.php

 require_once 'core/init.php';

$user = DB::get_instance()->query("Select * from users");
if($user->error()){
    echo "No user";
}else{
    echo "Ok";
}

I am not getting the reason due to which execute return false every time.

1 Answer

Serhii Lihus
Serhii Lihus
6,352 Points

Hi there Ashish!

Let's get straight to the point. Mainly error was in your connection string.

     "mysql:".Config::get("mysql/host").";
     dbname=".Config::get("mysql/db").";
     port=".Config::get("mysql/port")."\",\""
     .Config::get("mysql/username")."\",\""
     .Config::get("mysql/password")."\"");

A bit messy, but it's ok =)

How dsn connection should look like(from php.net manual):

$dbh = new PDO('mysql:host=localhost;dbname=test', $user, $pass);

Below you can find working sample. Change dbname, username and password(you can also add port to the config array).

<?php

class Config 
{
    private static $config = array();

    public static function setConfig($param_name, $value) 
    {
        self::$config[$param_name] = $value;
    }

    public static function getConfig($param_name) 
    {
        return self::$config[$param_name];
    }
}

Config::setConfig("mysql/host", "localhost");
Config::setConfig("mysql/db", "user");
Config::setConfig("mysql/username", 'username');
Config::setConfig("mysql/password", 'password');

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

    private function __construct()
    {
        try {
            $this->_pdo = new PDO(
                "mysql:host=".Config::getConfig("mysql/host").";"
                ."dbname=".Config::getConfig("mysql/db"),
                Config::getConfig("mysql/username"),
                Config::getConfig("mysql/password")
            );
        } catch(Exception $e) {
           echo $e->getMessage();
           exit();
        }
    }

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

        return self::$_instance;
    }

    public function query($sql, $params = array())
    {
        $this->_error = false;
        $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 = $this->_query->rowCount();
        } else {
            print_r($this->_query->errorInfo());
            $this->_error = true;
        }
    }

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

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


echo '<pre>';
$user = DB::get_instance();
$user->query("Select * from users");

if(!$user->error()) {
    print_r($user->getResults());
} else {
    echo "No users in db";
}