How to insert data in my table if a category selected

Hi there,

Is there a simple function that would insert data in a table (already created) if an term selected.

In human readable format, I was expecting to do something like this:

If Education category selected, insert “data” in table requests

I’ve tried this code but I’ve nothing registered in my table

global $wpdb, $current_user;
               get_currentuserinfo();
               $uid = $current_user->ID;
               $pid = $_GET['auction_id'];
               $tm = current_time('timestamp',0);
	       $post = get_post(get_the_ID());

		// Select the category of posted auction

			$req = "select term from ".$wpdb->prefix."terms"." where object_id='$post->ID'";
			$id_term = $wpdb->get_results($req);
			foreach( $id_term as $value)
			{
		// check if the auction category is education

			if($value->term == 522)
			{
					$wpdb-> query("insert into ".$wpdb->prefix."requests (pid, uid, datemade) values('$pid','$uid',$tm')");
				}
	 		}

Any help will be appreciated! Thanks in advance