PDOCrud Show specific crud columns and rename column

  
                            $pdocrud = new PDOCrud();
                            $pdocrud->colRename("first_name", "client name");
                            $pdocrud->crudTableCol(array("first_name","last_name"));
                            echo $pdocrud->dbTable("users")->render();
                            
SQLSTATE[42S22]: Column not found: 1054 Unknown column '' in 'field list'