PHP Loop within a loop

Question

In my database I have a table of "weeks" and a table of "workouts". I would like to achieve something like the following:

Week 1
- workout 1 title
- workout 1 content
- workout 2 title
- workout 2 content
- workout 3......
week 2
- workout 1 title
- workout 1 content
- workout 2 title
- workout 2 content
- workout 3......
week 3.....

I've trying something like:

function get_weekly_content() {

        $user_id = $this->session->userdata('id');

        $weeks = $this->db->select('week_no')->where('user_id', $user_id)->get('weeks');

        if($weeks->num_rows > 0) {
            foreach($weeks->result() as $row) {
                $week_no = $row->week_no;

                $workouts = $this->db->where('user_id', $user_id)->where('week_no', $week_no)->get('workouts');

                if($workouts->num_rows > 0) {
                    foreach($workouts as $workout) {
                        $workout_data[] = $workout;
                    }
                }


                $weekly_data[] = $workout_data;

            }
            return $weekly_data;
        }
    }

but maybe I have the wrong idea. I would then also need to display the data.

EDIT my question is, what would be the best way to achieve the above and get and array/object to loop through on a view page?

Thanks

have you initialized $workout_data

driangle
– driangle

2012-02-03 21:28:07 +00:00
Commented Feb 3, 2012 at 21:28 — driangle
– driangle, Commented Feb 3, 2012 at 21:28

Ben D · Accepted Answer · 2012-02-03 21:37:50Z

Looping with in a loop is just fine, and your approach is appropirate. However!

Generally speaking you shouldn't run mysql queries inside of loops if there is any way to avoid it because queries are quite slow this will really degrade the performance of your script. Otherwise, the idea is correct. Try to write a query outside of the loops that puts all the relevant user data into a keyed array and then pull the information from the array while you're looping.
You're going to see problems with this line: $weekly_data[] = $workout_data; if $workouts->num_rows > 0... if it's the first loop, it will throw an error because $workout_data won't be set, and if it's subsequent loops then on any week that doesn't have results, it will display the previous week's data. You can fix this by setting/resetting $workout_data at the top of the inner loop:

$workout_data = array(); 
if($workouts->num_rows > 0) {
   foreach($workouts as $workout) {
      $workout_data[] = $workout;
   }
}

driangle · Accepted Answer · 2012-02-03 21:33:15Z

0

function get_weekly_content() {

        $user_id = $this->session->userdata('id');

        $weeks = $this->db->select('week_no')->where('user_id', $user_id)->get('weeks');
        $weekly_data = array();
        if($weeks->num_rows > 0) {
            foreach($weeks->result() as $row) {
                $workout_data = array();
                $week_no = $row->week_no;

                $workouts = $this->db->where('user_id', $user_id)->where('week_no', $week_no)->get('workouts');

                if($workouts->num_rows > 0) {
                    foreach($workouts as $workout) {
                        $workout_data[] = $workout;
                    }
                }


                $weekly_data[$week_no] = $workout_data;
            }
        }
        return $weekly_data;
    }

Then access the data:

$weekly_data = get_weekly_content();

foreach( $weekly_data as $week_no => $workout_data){
  // do something with it.
}

That being said, I agree with @Ben D, you should think about your query and create one that can return all the results at once.

answered Feb 3, 2012 at 21:33

driangle

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1 Comment

Harry Over a year ago

How could you go about doing that? I agree one query would be ideal

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