Question

So I have a query that I am returning all of the items into a mysql_fetch_array. Now, I know I could write another query and just select the items I need into a seperate query but, is there a way to just filter from the larger query what I want dependent on $_GET?

So, in english the user comes from a hyperlink that has ?id=1 and I peform a while that gets the all the values but, only display the $_GET[‘id’] items in a list

<?php //give ma all values but only echo out list of the $_GET['id'] in the url
  while ($row = mysql_fetch_array($result) {
    $id = $rowvideo["id"];
    $title = $rowvideo["title"];
    $length = $rowvideo["length"];
}
echo("<li><a href='#'>". $title." " .$length. "</a></li>");
?>

Hope this makes sense. Thank you all.

Answer 1

If you do not want a second query to get just what you need, a simple-if-statement in your loop should work:

<?php
$getId = isset($_GET['id']) ? $_GET['id'] : false;
//give ma all values but only echo out list of the $_GET['id'] in the url
while ($row = mysql_fetch_array($result)) {
    $id = $row["id"];
    $title = $row["title"];
    $length = $row["length"];

    if ($id == $getId) {
        echo("<li><a href='#'>". $title." " .$length. "</a></li>");
    }
}
?>

Note that I declared $getId outside of the loop to prevent having to use isset() during every iteration. If you don’t verify if it’s set and attempt to use it it will throw an undefined index warning – assuming you have error_reporting turned on (with that level enabled).

Alternatively, you could use PHP’s array_filter() on the data after you’ve parsed it all:

$results = array();
while ($row = mysql_fetch_array($result)) $results[] = $row;
if (isset($_GET['id'])) {
    $filtered = array_filter($results, function($element) use ($_GET['id']) { return ($element['id'] == $_GET['id']); });
    $results = $filtered;
}
foreach ($results as $result) {
    echo("<li><a href='#'>". $result['title']." " .$result['length']. "</a></li>");
}

My personal opinion would be to be more efficient and write the second query though, assuming of course you don’t actually need all of the results when an id is specified. It would be as simple as:

if (isset($_GET['id']) && is_numeric($_GET['id'])) {
    $query = 'SELECT id, title, length FROM table WHERE id=' . (int)$_GET['id'];
} else {
    $query = 'SELECT id, title, length FROM table';
}
// your existing code as-is