Smart $ Fast database select and get single data - field entry :)

[eluser]flash_back[/eluser]
here is thing, when I have just one or maybe two database entry to get i use this code

Code:

$this->db->where('data', $data)->get($this->_table)->row()->table_field;

but what do you think, when we get data from DB from this code, does this code select all table fields or just included one?!?