How to retrieve database error from CodeIgniter

[eluser]DarthVinsus[/eluser]
[quote author="adwin" date="1211548804"]use this

Code:

$this->db->_error_message();

will return empty if no error.[/quote]


the error number $this->db->_error_number(), where I can look? I will know if there is a list of these error and whre I can look for it?