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POIncrementing child element database fetching in codeigniter
 

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  1. POIncrementing child element database fetching in codeigniter
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    <p>I'm trying to fetch a series of ids from a database table that includes cross-referencing - each element, a "topic", includes a column for "parent topic" that is within the same table. Given a single parent topic, I want to build an array of all the subtopics that have it as their parent, and then all of the subtopics of those topics, etc.</p> <p>This doesn't seem like it's that hard, but as a self-taught programmer I feel I'm using all the wrong tools. The <code>merge-array()</code> and <code>var_dump()</code> sections, in particular, feel wrong and I'm not sure about the overall approach. What should I replace these elements with?</p> <pre><code>function get_subtopics($parent_topic) { //returns an array of subtopics minus the first $all_subs = array(); $query = $this-&gt;db-&gt;get_where('topics', array('parent_topic' =&gt; $parent_topic)); $subs = $query-&gt;result_array(); $resubs = array(); $query-&gt;free_result(); //push subs to all_subs //while the subs array has members, find their child while (count($subs)&gt;0) { foreach ($subs as $s) { $query = $this-&gt;db-&gt;get_where('topics', array('parent_topic' =&gt; $s['id'])); $resubs = array_merge($resubs, $query-&gt;result_array()); $query-&gt;free_result(); } $all_subs = array_merge($all_subs, $resubs); var_dump($resubs); } //Returns an array of ids return $all_subs; } </code></pre> <p>EDIT: The objective of this is to form a "pool" of topics from which problems will be drawn for a random generator - I'm trying to get all of the subtopics into one array, with no tree structure to differentiate them. Users that specify a parent topic, like "math" should get an even mix of math subtopics like "algebra", "algebra:quadratics" or "calculus" from which problems will be drawn. Hope that clarifies a little.</p>
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