Sum the seconds from a TIME type column using Codeigniter's active record query building methods

Question

I would like to sum a column of a database with certain WHERE criteria then display it on the webpage, but am unsure of how to do so.

Here is what I have so far for my function in my controller.

public function get_hours() {
    $user_email = $this->session->userdata('USER_EMAIL');
    $this->db->where('USER_EMAIL', $user_email);
    $this->db->select_sum('USER_WORK_HOURS');
    $data = $this->db->get('user_hours');
    $hours = $data->row()->USER_WORK_HOURS;
    echo $hours;
}

This will take me to a blank page and not display anything.

I have also tried to echo out $data, but get an error saying it could not convert it to string.

The column that I am trying to sum is a TIME type column.

Answer 1

Try this:

public function get_hours()
{

$user_email = $this->session->userdata('USER_EMAIL');

$this->db->select('SEC_TO_TIME( SUM( TIME_TO_SEC( `USER_WORK_HOURS` ) ) ) AS totalHours'); 
$this->db->where('USER_EMAIL', $user_email);
$hours= $this->db->get('user_hours')->row()->totalHours;

echo $hours;

}