two foreach connect

Hello everyone,
I have a question.
In my website I often have to link two different "foreach".
I usually do it like this

PHP Code:

foreach ($view_category_main as $main):
    $SQL = "SELECT * FROM db_todo_mission WHERE db_todo_mission.tb_todo_mission_main = ".$main['category_id']." GROUP BY db_todo_mission.tb_todo_mission_sub";
    $query = $this->db->query($SQL);
    foreach ($query->result() as $sub):
        echo $sub->tb_todo_mission_sub;
    endforeach;
endforeach; 


Now i wonder if there is a more elegant way to store it in modal and then have it retrieved?

If you follow the model-view-controller pattern, the database query should be in a model and the output should in a view.

You could do something like this:

MODEL

PHP Code:

// Add & in front of $main
foreach ($view_category_main as &$main)
{
    $SQL = "SELECT * FROM db_todo_mission WHERE db_todo_mission.tb_todo_mission_main = ".$main['category_id']." GROUP BY db_todo_mission.tb_todo_mission_sub";
    $query = $this->db->query($SQL);
    // Store the results for each category
    $main['sub'] = $query->result()
} 


VIEW

PHP Code:

foreach ($view_category_main as $main):
    // Loop on the sub array for each category
    foreach ($main['sub'] as $sub):
        echo $sub->tb_todo_mission_sub;
    endforeach;
endforeach;