What potential issues can arise when sorting database results in PHP, especially when dealing with timestamps stored as varchar?

When sorting database results in PHP with timestamps stored as varchar, potential issues can arise due to the data type mismatch between varchar and timestamp. To solve this issue, you can convert the varchar timestamps to actual timestamp data type before sorting the results. This can be achieved by using the strtotime() function in PHP to convert the varchar timestamps to Unix timestamps for accurate sorting.

// Assuming $results is an array of database results with varchar timestamps

// Convert varchar timestamps to Unix timestamps
foreach ($results as $key => $result) {
    $results[$key]['timestamp'] = strtotime($result['timestamp']);
}

// Sort the results by timestamp in ascending order
usort($results, function($a, $b) {
    return $a['timestamp'] - $b['timestamp'];
});