I'm familiar with the unix timestamp and date() function.
I created a row in my database for the date and instead of using Timestamp I made it an integer.
Here's part of my code:
$date=mktime();
$query2="INSERT into classifieds_ad (classifieds_Name,classifieds_Ad,classifieds_category_ID,classifieds_m_date) values ".
"('".$_GET['classifieds_Name']."','".$_GET['classifieds_Ad']."','".$_GET['classifieds_category_ID']."','$date')";
The correct date is posted when an item is listed, I just don't know how to select items that have been posted within 30 days.