ASC DESC在同一链接中

Question

if (isset($_GET['order']) && $_GET['order'] == 'category')
{

    $sql .= " ORDER BY category ".$_GET["direction"];
}

<a href='?order=category&direction=ASC'>

When the user clicks second time on the link I want to order the table in DESC order. I have the a-z order I need to reverse them when the user clicks on the same link.

Answer 1

Simply check what is contained in the $_GET['direction'] and reverse it each time the submit is run.

Also, to take care of page reloads, save the value of previous direction in session.

$dir = 'DESC'; // set default for first execution
@session_start(); // start the session if it isn't already started.
if(!empty($_GET['direction'])){
  $dir = $_GET['direction'] == 'ASC' ? 'ASC' : 'DESC'; // avoids SQL injection.
  $_SESSION['direction'] = $dir;
}elseif(!empty($_SESSION['direction'])){
  $dir = $_SESSION['direction'];
 }
if (isset($_GET['order']) && $_GET['order'] == 'category') {
    $sql .= " ORDER BY category ".$dir;
}

$reverseDir= $dir =='DESC' ? 'ASC' : 'DESC'; //reverses the direction to be used in the link
<a href='?order=category&direction='<?php echo $reverseDir;?>>