An MYSQLI tool class for encapsulating with interfaces

<?PHPclassDaomysqliImplementsi_dao{//object instances of this class     Private Static $instance; //result set     Private $result _row; //configuration Information     Private $_host; Private $_root; Private $_dbname; Private $_PW; Private $_port; Private $_charset; //mysqli instantiating an object     Private $_mysqli; Private function__construct ($option){       $this->_initarray ($option); $this-_initmysqli (); }     Private function__clone () {}//define a singleton pattern      Public Static functionGetsingleton (Array $option=Array()){      if(! (Self::$instanceinstanceof Self)) { Self::$instance=NewSelf$option); }         returnSelf::$instance; }     Private function_initarray ($option){       $this->_host=isset($option[' Host ']?$option[' Host ']: '; $this->_root=isset($option[' Root ']?$option[' Root ']: '; $this->_dbname=isset($option[' dbname '])?$option[' dbname ']: '; $this->_pw=isset($option[' PW '])?$option[' PW ']: '; $this->_port=isset($option[' Port ']?$option[' Port ']: '; $this->_charset=isset($option[' CharSet '])?$option[' CharSet ']: ';
}     Private function_initmysqli () {//instantiating a Mysqli object      $this->_mysqli=NewMysqli ($this->_host,$this->_root,$this-&GT;_PW,$this->_dbname,$this-_port); if($this->_mysqli->Connect_errno) {        Echo"Connection failed."$this->_mysqli->Connect_error; Exit; }       //setting Character Set encoding       $this->_mysqli->set_charset=$this-_charset; }     //Methods for querying      Public functionQuery$sql= ' '){      $result=$this->_mysqli->query ($sql); if(false==$result){        Trigger_error("Execution failed, your SQL statement has a problem.")$sql." Error message ".$this->_mysqli->error); return false; }      $this->result_row=$result; return $result; }     //methods for non-queries      Public functionExecu ($sql= ' '){       $result=$this->query ($sql); if(false==$result){         return false; }Else{         Echo"Successful Execution"; }     }     //querying all the records      Public functionFetchall ($sql= ' '){      $result=$this->query ($sql); if(false==$result){       return false; }      $rows=Array();  while($row=$result-Fetch_array (MYSQLI_ASSOC)) {         $rows[]=$row; }        $result-Free (); return $rows; }     //Query a record      Public functionFetchrow ($sql= ' '){       $result=$this->query ($sql); if(false==$result){         return false; }       $row=$result-Fetch_array (MYSQLI_ASSOC); $result-Free (); return $row?$row:false; }     //Query the first field of a record      Public functionFetchone ($sql= ' '){       $result=$this->query ($sql); if(false==$result){         return false; }       $row=$result-Fetch_array (Mysqli_num); $result-Free (); return $row?$row[0]:false; }     //query all records for a field      Public functionFcoulumn ($sql,$coulumn){        $result=$this->fetchall ($sql); if(false==$result){          return false; }        $rows=Array(); foreach($result  as $row){        $rows[]=$row[$coulumn]; }        return $rows; }     //method to provide escape      Public functionEscapedata ($data= ' '){            }     //gets the number of records affected      Public functionAffectedrow () {$affected _row=$this->_mysqli->affected_rows; if($affected _row==0){        Echo"Operation succeeded, but not affected"; }      return $affected _row; }     //gets the number of records affected by the result      Public functionResultrow () {$num _rows=$this->result_row->num_rows; $this->result=NULL; return $num _rows; }     //get the latest auto-generated IDs      Public functionLastinsertid () {return $this->_mysqli->insert_id; }   }?>

An MYSQLI tool class for encapsulating with interfaces