Codeigniter: check mysql connection

To check error in mysql connection, we need to change ENVIRONMENT to Production. Here is the example:

    //define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'development');

    //define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'testing');

    define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'production');

There are two ways to catch error in our controller:

1. Using dblib

        $this->load->dbutil();

        if ($this->dbutil->database_exists('myca')) {

            // Connection ok

        } else {

            // Connection fail

        }

2. Checking error in db

        $this->load->database();

        $errhandle = $this->db->error();

        if ($errhandle['code']==0) {

            // Connection ok

        } else {

            // Connection fail

            // to dump error code var_dump( $this->db->error());

        }

Tested on PHP 7.2 and Codigniter 3.1.10