pmpro_category_level_functions

/** Accepts a level ID and returns all categories protected by that level(id) **/
function pmpro_getCategoriesForLevel($level_id)
{
	global $wpdb;

	$sql = "SELECT category_id FROM {$wpdb->pmpro_memberships_categories} WHERE membership_id = %d";
	$sql = $wpdb->prepare($sql, $level_id);

	return $wpdb->get_results($sql);
}

/** Accepts one (string = the slug value for the category) as the argument & returns list of membership levels for that category **/
function pmpro_getLevelsForCategory($category_slug)
{
	global $wpdb;

	// Get all categories in the s
	$categories = get_categories();
	$to_find = array();

	// Make even a single slug into an array for processing purposes.

	foreach($categories as $c) {
		if ($category_slug == $c->slug ) {
			$to_find = $c->cat_ID;
			break;
		}
	}

	$sql = "SELECT membership_id AS level_id FROM {$wpdb->pmpro_memberships_categories} WHERE category_id = %d";

	// Return the list of IDs for the category
	return $wpdb->get_results( $wpdb->prepare( $sql, $to_find ) );
}