If I have this array:
array(1) {
["ID"]=>
string(1) "3"
}
array(1) {
["ID"]=>
string(1) "6"
}
array(1) {
["ID"]=>
string(1) "9"
}
And I want to have an output of this: 3, 6, 9
How can I concatenate or implode those array values to put in a variable so that I will use that variable with a value of like this: 3, 6, 9 in this: $this->db->set('SecondaryRoleID', $imploded);
Use the function array_column to extract the ID from each element into a single-dimensional array, then implode as usual:
echo implode(',', array_column($array, 'ID'));
If you are running PHP earlier than 5.5 then array_column is not available out of the box, so you have to provide equivalent code such as
echo implode(',', array_map(function($r) { return $r['ID']; }, $array));
That said, your proposed usage of the final result (sticking a comma-separated integer list representing item ids into a database field) is unusual and possibly wrong. For many-to-many relationships (each user can have many roles, and each role can be assigned to many users) the standard implementation is to use a join table, keeping your database schema normalized.
