How to recover from failed database query in CodeIgniter?

You could modify the Exceptions class to... throw an exception. Just create MY_Exceptions.php in application/core/:

class MY_Exceptions extends CI_Exceptions {    function show_error($heading, $message, $template = 'error_general', $status_code = 500)    {        // BEGIN EDIT        if ($template === 'error_db')        {            throw new Exception(implode("\n", (array) $message));        }        // END EDIT        set_status_header($status_code);        $message = '<p>'.implode('</p><p>', ( ! is_array($message)) ? array($message) : $message).'</p>';        if (ob_get_level() > $this->ob_level + 1)        {            ob_end_flush();        }        ob_start();        include(APPPATH.'errors/'.$template.'.php');        $buffer = ob_get_contents();        ob_end_clean();        return $buffer;    }}

Then use a try/catch block to check for the error and attempt to run another query:

try {    $this->db->get('table1');} catch (Exception $e) {    $this->db->get('table2');}

It's kind of a sloppy workaround, but it gets the job done.

You might want to take a look at transactions as well:

Running Transactions

To run your queries using transactions you will use the $this->db->trans_start() and $this->db->trans_complete() functions as follows:

$this->db->trans_start();
$this->db->query('AN SQL QUERY...');
$this->db->query('ANOTHER QUERY...');
$this->db->query('AND YET ANOTHER QUERY...');
$this->db->trans_complete();

You can run as many queries as you want between the start/complete functions and they will all be committed or rolled back based on success or failure of any given query.

One of the ways to achieve this is

First.

Set  ['db_debug'] = FALSE; in config/database.php

Then,

In your model -

public function attempt_one($data) {  //build your query ....  $query_result = $this->db->insert('table_name');  if(!$query_result) {     $this->error = $this->db->_error_message();     $this->errorno = $this->db->_error_number();     return false;  }  return $something;}public function attempt_two() {  //another query goes in here ...}

in your controller -

public function someAction (){  //some code   $data = $some_data;  $result1 = $this->yourmodel->attempt_one($data);  if($result1 === false)  {    //Some code to send an email alert that first query failed with error message     //and/or log the error message/ number     $result2 = $this->yourmodel->attempt_two($data);  }}

Just use

$this->db->simple_query() 

rather than

$this->db->query()

Simple Query will return true/false.