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POhow to loop over looped elements in Php?
 

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  1. POhow to loop over looped elements in Php?
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    <p>I'm creating a tree-structure of categories with parentid's which can be called from children in such a way:</p> <pre><code>ID | Name | ParentID 1 1 0 2 2 1 3 3 2 4 4 1 </code></pre> <p>Resulting in this:</p> <pre><code>1 = 1 2 = 1 -&gt; 2 3 = 1 -&gt; 2 -&gt; 3 4 = 1 -&gt; 4 </code></pre> <p>which means <strong>3 is a child of 2</strong>, which is a child of 1.</p> <p>when trying to get this idea (with the -> to show what relations are set) I only get to the second grade (1 -> 2) but not to the third (1->2->3) because of the looping function I use for it.</p> <pre><code>//put all ID's in an array while ($row2 = $connector-&gt;fetchArray($result2)){ $id = $row2['ID']; $parents[$id] = $row2['name']; } // show the tree-structure while ($row = $connector-&gt;fetchArray($result)){ if($row['parentid']!=0)echo $parents[$row['parentid']].' -&amp;gt; '; echo $row['name'].' - &amp;nbsp;&amp;nbsp; '; echo '&lt;br&gt;'; } </code></pre> <p>I'd like two things to change:</p> <blockquote> <ol> <li>have the code automatically generate a tree sized as necessary.</li> <li>in the while-loops i have to select the $result twice (once as $result, once as $result2) to make it work. these $result's have exactly the same database-query:<br/><code>SELECT ID,name,parentid FROM categories</code></li> </ol> </blockquote> <p>to fetch results from. I'd like to only declare this once.<br/> <br/> <br/> <br/> <strong>Thanks for all the good answers. I've gone with the easiest, less-code-to-implement approach:</strong></p> <pre><code>$result = $connector-&gt;query('SELECT ID,name,parentid FROM categories'); // Get an array containing the results. $parents = array(); while ($row = $connector-&gt;fetchArray($result)){ $id = $row['ID']; $parents[$id] = array('ID' =&gt; $row['ID'],'name' =&gt; $row['name'],'parentid' =&gt; $row['parentid']); } foreach ($parents as $id =&gt; $row){ $pid=$id; $arrTmp= array(); do { // iterate through all parents until top is reached $arrTmp[]=$pid; $pid = $parents[$pid]['parentid']; }while ($pid != 0); $arrTmp = array_reverse($arrTmp); foreach($arrTmp as $id){ echo $parents[$id]['name'].' -&amp;gt; '; } echo '&lt;br&gt;'; } </code></pre>
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