使用array_merge_recursive合并2个数组不能正常工作

Question

My database has 2 columns. the person's ID is repeated 5 times in 1 column and each its paired in another column with a question answer Something like this:

ID  Answer
1   A1
1   A4
1   A2
1   A9
1   A3
12  A1
12  A11
12  A12
12  A17
12  A2

What i want to try to do is to merge all the answers into 1 array with its ID something like

array (
        [1] => array ( 0 => 'A1', 1 => 'A4', 2 => 'A2', 3 => 'A9', 4 => 'A3'),
        [12] => array ( 0 => 'A1', 1 => 'A11', 2 => 'A12', 3 => 'A17', 4 => 'A2')
        )

My code is as follows:

foreach ($quiz_answers as $aq => $aa)
            {
                $array_loop = array(  $aa['response_id'] => array( $aa['answer'] ) );
                $ss = array_merge_recursive($array_loop, $array_loop);

            }

My Problem is that somehow the loop doesnt merge in the desired way and i only get 2 outputs. I am not very good at manipulating arrays and probably i need another function but i am not quite sure what i am missing. I've tried using another variable in array_merge_recursive($anotherVariable, $array_loop); but this doesnt work either.

Answer 1

Simply change your foreach loop to construct the resulting array how you desire.

foreach ($quiz_answers as $aa) {
    $ss[$aa['response_id']][] = $aa['answer'];
}

This gives an $ss array as you want:

array(
    1  => array('A1', 'A4', 'A2', 'A9', 'A3'),
    12 => array('A1', 'A11', 'A12', 'A17', 'A2'),
)