php 5 mysqli wrapper - command

// wrapper for mysqli statement object
class MySqlCommand{

//
// private members
//

private $Statement; // prepared statement

//
// public members
//

public $CommandText; // sql to execute
public $Connection; // mysqli object
public $Parameters = array(); // array of input parameters
public $Results = array(); // array of output parameters

//
// constructor
//

public function __construct($CommandText = '', $Connection = ''){

 $this->CommandText = $CommandText;
 $this->Connection = $Connection;
}

//
// private methods
//

// bind input parameters
private function BindParameters(){

 if(count($this->Parameters)){

  // determine type of input parameter (i)nteger/(d)ouble/(s)tring
  $types = '';
  foreach ($this->Parameters as $Parameter){

   if(is_int($Parameter))
    $types .= 'i';
   elseif(is_float($Parameter))
    $types .= 'd';
   else
    $types .= 's';
  }

  // $this->Statement->bind_param($types, $this->Parameters[0], $this->Parameters[1], ...);
  call_user_func_array(array($this->Statement, 'bind_param'), array_merge(array($types), $this->Parameters));
 }
}

// log errors
private function handle_exception(){

 $oMySqlError = new MySqlError();
 $oMySqlError->Message = $this->Connection->Error();
 $oMySqlError->CommandText = $this->CommandText;
 $oMySqlError->Parameters = $this->Parameters;
 $oMySqlError->Log();
 $oMySqlError = null;
}

//
// public methods
//

// helper method for adding bound parameters
public function AddParameter(&$parameter){
 $this->Parameters[] = &$parameter;
}

// close the statement if it hasn't been closed already
public function Close(){

 if(is_object($this->Statement))
  $this->Statement->close();
}

// execute a non-query, like insert, update, delete
public function ExecuteNonQuery(){

 try{

  // prepare statement
  if(!$this->Statement = $this->Connection->Prepare($this->CommandText))
   throw new Exception();

  // bind input parameters
  $this->BindParameters();

  // execute statement
  if(!$this->Statement->execute())
   throw new Exception();
 }
 catch (Exception $e){

  $this->handle_exception();
 }
}

// return a data reader from a select statement
public function ExecuteReader(){

 try{

  // prepare statement
  if(!$this->Statement = $this->Connection->Prepare($this->CommandText))
   throw new Exception();

  // bind input parameters
  $this->BindParameters();

  // execute statement
  if(!$this->Statement->execute())
   throw new Exception();
 }
 catch (Exception $e){

  $this->handle_exception();
 }

 // create and return a new data reader for statement
 $oDataReader = new MySqlDataReader($this->Statement);
 return $oDataReader;
}

// return a scalar value
public function ExecuteScalar(){

 try{

  // prepare statement
  if(!$this->Statement = $this->Connection->Prepare($this->CommandText))
   throw new Exception();

  // bind input parameters
  $this->BindParameters();

  // execute statement
  if(!$this->Statement->execute())
   throw new Exception();
 }
 catch (Exception $e){

  $this->handle_exception();
 }

 // create a data reader
 $oDataReader = new MySqlDataReader($this->Statement);
  // bind the result
  $oDataReader->AddResult($result);
 // execute the reader
 if(!$oDataReader->Read())
  $result = null;
 $oDataReader = null;

 // return the result
    return $result;
}

}
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