Codeigniter query builder class results

No. Not really.You can, however, control what the model returns. Keep in mind that an empty resultset, for example, is not necessarily a "failed" query. There's a lot of use cases where an empty resultset may be a good thing.

After actually running the query you will get an object with the result

for instance, when selecting, you can do $result = $this->db->get() and your $result variable will become an object with a lot of information you can access:

Number of returned rows: $result->num_rows();Returned contents: $result->result();Specific rows: $result->row(0);Specific field in a specific row: $result->row(3)->field_name;

When inserting or updating, $this->db->affected_rows() becomes available so you can check how many rows were updated or inserted. Inserts also make $this->db->insert_id() available in case you need the table's primary key value for the row you inserted.

Thus, you are in control of the logic.

when selecting, I usually do:

$query = $this->db->get();if ($query->num_rows() == 0){  return false;}else{  return $query->row(0);}

Then I check, in the controller, if the model returned false or a real resultset (sometimes I just return true instead of the actual resultset if I'm just checking for something to exist). You can tailor the results to your needs.

When inserting, I usually check:

if ($this->db->affected_rows() != 0){  return $this->db->insert_id();}else{  return false;}

(in the controller, a false being returned would be handled as an "insertion failed").

To answer your question more globally: No, nothing really happens by default, but Codeigniter gives you everything you need to tailor the behavior of your site to your specific needs and tastes