Calculating time difference between two db values for multiple rows - php

Question

I have a database which holds two timestamps (date_ticket_reported, date_ticket_resolved), I want to caluclate the average time difference between these times for each resolved_by user_id.
Each row has a (resolved_by) column which corresponds to a user_id.
There will be multiple rows, for each user_id.
I have tried various approaches including the following.
ticket_model.php code
public function get_resolved_time_by_user($user_id){
$query1 = $this->db->select('resolved_date')->from('tickets')->where('resolved_by',$user_id)->get();
$resolved1 = $query1->row();
$query2 = $this->db->select('ticket_date_reported')->from('tickets')->where('resolved_by',$user_id)->get();
$reported1 = $query2->row();
$resolved2 = $resolved1->resolved_date;
$reported2 = $reported1->ticket_date_reported;
foreach($resolved2 as $row){
//Convert them to timestamps
$reported_dateTimestamp = strtotime($resolved2);
$resolved_dateTimestamp = strtotime($reported2);
$diff = $resolved_dateTimestamp - $reported_dateTimestamp;
return $diff;
}
}
Ticket view code
<p> Average Resolve Times <?php echo $this->ticket_model->get_resolved_time_by_user($user_id); ?> </p>
So to summarise; I want to display the average time between date_ticket_reported, date_ticket_resolved. For each user_id specified.
Any help would be awesome!
I have tried Malkhazi Dartsmelidze answer,
$this->db->query("SELECT
AVG(TIMESTAMPDIFF(SECOND, resolved_date, ticket_date_reported)) as timediff,
resolved_by as user
FROM tickets
GROUP BY resolved_by");
I get an error saying Object of class CI_DB_mysqli_result could not be converted to string
Where you say resolved_by as user. Should "user" be the user_id? ie should it say "resolved_by as user_id"?

Answer 1

You Can run only One Query With Myqsl:
SELECT
AVG(TIMESTAMPDIFF(SECOND, resolved_date, ticket_date_reported)) as timediff,
resolved_by as user
FROM tickets
GROUP BY resolved_by
This returns Average Time Difference in Seconds for Each User

Answer 2

Try this
$resolved2 = $resolved1->resolved_date;
$reported2 = $reported1->ticket_date_reported;
$diff = $resolved2 - $reported;
And then echo $diff and check what you are getting in $diff,