php - Grocery crud filtering issue -

i want know how filter retrieval of records in table. using grocery_crud on top of codeigniter. don't know how put condition on results retrieved. example,i have customers crud , want retrieve ones in new york. please help

this function , want narrow results before rendering view

    public function employees(){         $crud = new grocery_crud();         $crud->set_subject('employees');         $crud->set_table('employees');         $crud->columns('firstname','email');         $crud->display_as('firstname','first name');         $crud->display_as('email','e-mail address');         $crud->required_fields('email');         $output = $crud->render();          $this->output($output);     } 

you use where function:

$crud->where('city','new york'); 

there lot of nifty functions available!