Issue with Classes, Instances and Objects

Question

I'm fairly new to PHP; however I think I have a good grasp on it, but I'm having an issue understanding why I'm not able to access a second version of a connect to DB class I have.

I connect globally to the first one in a config script.

$db = new db(array('login info'));

I access it in my controller using the following.

public $db;
public function __construct(){
    $this->db = $GLOBALS['db'];
}

Then inside my controller I have a function where I create a new instance of this to connect to a different DB.

$ordersDB = new db(array('login info'));

Now I would like to access each database separately using something like

$this->db->select("SELECT * FROM ada Yada 

and

$ordersDB->select("SELECT * FROM Yada Yada

However both are still accessing the first db. I know this because I am getting a table does not exist error when executing the second one and it tells me what db its querying. However a var_export of them shows they are infact different! Am I completely misunderstanding how classes work or can I only have one DB open at a time? Thanks for any help.

Edit: Is this what you are looking for?

$db = new db(array(connect info));
$controller = new controller();
$controller->connectToSecondDB();

class db {

    public $dbHost;
    public $dbUser;
    public $dbName;
    public $dbPassword;

    public function __construct() {
       $arguments = func_get_args();

       if(!empty($arguments)){
          foreach($arguments[0] as $key => $property){
            if(property_exists($this, $key)){
                $this->{$key} = $property;
            }
           }
       }
    }

  public function connect() {            
        if(!isset(self::$connection)) {       
            self::$connection = new mysqli($this->dbHost, $this->dbUser, $this->dbPassword, $this->dbName);
        }
}

class controller {
   public $db;
   public function __construct(){
      $this->db = $GLOBALS['db'];
   }

   public function connectToSecondDB(){
      $ordersDB = new db(array(connect info));
      $ordersDB->select("SELECT * FROM `customer` WHERE email = 'email@address.com' LIMIT 1")
      $this->db->query("SQL");
   }
}

EDIT Select Query Function

private function _sel($table, $where="", $order_by="", $limit="", $group_by="",$database = NULL){
        if($database === NULL) {  $database = $this->db; }
        if($limit == 1){ $single = true; }else{ $single = false; }

        //if( is_array($where) ){ $this->_buildWhere(); }
        $where = (strlen($where) > 0) ? "WHERE $where " : $where;       
        $group_by = (strlen($group_by) > 0) ? "GROUP BY $group_by " : $group_by;        
        $order_by = (strlen($order_by) > 0) ? "ORDER BY $order_by " : $order_by;        
        $limit = (strlen($limit) > 0) ? "LIMIT $limit " : $limit ;

        $sql = "SELECT * 
                FROM `$table` 
                $where 
                $group_by 
                $order_by 
                $limit";
        // Debug

//if(INCLUDE_CHECK){ echo "<HR>".$sql."<HR>";   }
        $results = $database->select($sql); 
        if($single && count($results) > 0 ){
            return($results[0]);
        }else{
            return($results);
        }
    }

Answer 1

A solution is to reuse your $controller object. Add a query method. Then you can run the query separate from the connection method so the controller object can be reused

You need error checking each step along the way.

Note that I removed $this->db->query("SQL"); as I am not sure what exactly it did. The concept in the answer should get you started redesigning your class.

UPDATE Based on comment, I changed the $db from a super global and passed it to the controller object.

$db = new db(array(connect info));
// try passing the $db object so it does not need to be a super global
$controller = new controller($db);
// You can keep your $controller object as a global - I use a session variable for this to reuse it between pages.
$controller->connectToSecondDB();
// run the query separate from the connection so the controller object can be reused
$result = $controller->ordersQuery("SELECT * FROM `customer` WHERE email = 'email@address.com' LIMIT 1")


class db {

    public $dbHost;
    public $dbUser;
    public $dbName;
    public $dbPassword;
    public $connection;

    public function __construct() {
       $arguments = func_get_args();

       if(!empty($arguments)){
          foreach($arguments[0] as $key => $property){
            if(property_exists($this, $key)){
                $this->{$key} = $property;
            }
           }
       }
    }

  public function connect() {            
        if(!isset($this->$connection)) {       
            $this->connection = new mysqli($this->dbHost, $this->dbUser, $this->dbPassword, $this->dbName);
        }
}

class controller() {
   public $db;
   public $ordersDB;    // ADD THIS

   public function __construct($db2){
      $this->db = $db2;
   }

   public function connectToSecondDB(connect info){
      $ordersDB = new db(array(connect info));
   }

   public function ordersQuery($sql){
      $this->ordersDB->query($sql)
      // Fetch and return you result set here
   }

}