php - How to select and decode column value in codeigniter query -

i have table users data password column encoded using encrypt library in codeigniter. now, want select encoded column decode , compare password's user input (login validation). here's code. inserted value this:

$this->db->insert("my_table",array("username"=>$this->input->post("username"),"password"=>$this->encrypt->encode($this->input->post("password")))); 

for validate input way:

 $data = $this->db->get("mytable");     foreach($data $d){      if($d["username"] == $this->input->post("username") && $d["password"] == $this->encrypt->decode($this->input->post("password")){     //success     break;     } } 

this works fine me but, want shorter , cleaner way this. know, also, future coding practice. here's have done far:

$this->db->get_where("my_table",array($this->encrypt->decode("password")=>$this->input->post("password"))); 

but yeah! returns error message. error says:

unknown column '0' on clause 

the problem setting decoded password database column.

array($this->encrypt->decode("password")=>$this->input->post("password")) 

what need doing more like:

array("password" => $this->encrypt->decode("password"))