protected static function get_where_sql( $args = array() ) {
		global $wpdb;

		$where_conditions = array();
		$where            = '';

		// id
		if ( false !== $args['id'] ) {
			$id_in = implode( ',', wp_parse_id_list( $args['id'] ) );
			$where_conditions['id'] = "id IN ({$id_in})";
		}

		// user_id
		if ( ! empty( $args['user_id'] ) ) {
			$user_id_in = implode( ',', wp_parse_id_list( $args['user_id'] ) );
			$where_conditions['user_id'] = "user_id IN ({$user_id_in})";
		}

		// inviter_id. 0 can be meaningful, in the case of requests.
		if ( ! empty( $args['inviter_id'] ) || 0 === $args['inviter_id'] ) {
			$inviter_id_in = implode( ',', wp_parse_id_list( $args['inviter_id'] ) );
			$where_conditions['inviter_id'] = "inviter_id IN ({$inviter_id_in})";
		}

		// invitee_email
		if ( ! empty( $args['invitee_email'] ) ) {
			if ( ! is_array( $args['invitee_email'] ) ) {
				$invitee_emails = explode( ',', $args['invitee_email'] );
			} else {
				$invitee_emails = $args['invitee_email'];
			}

			$email_clean = array();
			foreach ( $invitee_emails as $email ) {
				$email_clean[] = $wpdb->prepare( '%s', $email );
			}

			$invitee_email_in = implode( ',', $email_clean );
			$where_conditions['invitee_email'] = "invitee_email IN ({$invitee_email_in})";
		}

		// class
		if ( ! empty( $args['class'] ) ) {
			if ( ! is_array( $args['class'] ) ) {
				$class_names = explode( ',', $args['class'] );
			} else {
				$class_names = $args['class'];
			}

			$cn_clean = array();
			foreach ( $class_names as $cn ) {
				$cn_clean[] = $wpdb->prepare( '%s', sanitize_key( $cn ) );
			}

			$cn_in = implode( ',', $cn_clean );
			$where_conditions['class'] = "class IN ({$cn_in})";
		}

		// item_id
		if ( ! empty( $args['item_id'] ) ) {
			$item_id_in = implode( ',', wp_parse_id_list( $args['item_id'] ) );
			$where_conditions['item_id'] = "item_id IN ({$item_id_in})";
		}

		// secondary_item_id
		if ( ! empty( $args['secondary_item_id'] ) ) {
			$secondary_item_id_in = implode( ',', wp_parse_id_list( $args['secondary_item_id'] ) );
			$where_conditions['secondary_item_id'] = "secondary_item_id IN ({$secondary_item_id_in})";
		}

		// type
		if ( ! empty( $args['type'] ) && 'all' !== $args['type'] ) {
			if ( 'invite' == $args['type'] || 'request' == $args['type'] ) {
				$type_clean = $wpdb->prepare( '%s', $args['type'] );
				$where_conditions['type'] = "type = {$type_clean}";
			}
		}

		/**
		 * invite_sent
		 * Only create a where statement if something less than "all" has been
		 * specifically requested.
		 */ 
		if ( ! empty( $args['invite_sent'] ) && 'all' !== $args['invite_sent'] ) {
			if ( $args['invite_sent'] == 'draft' ) {
				$where_conditions['invite_sent'] = "invite_sent = 0";
			} else if ( $args['invite_sent'] == 'sent' ) {
				$where_conditions['invite_sent'] = "invite_sent = 1";
			}
		}

		// accepted
		if ( ! empty( $args['accepted'] ) && 'all' !== $args['accepted'] ) {
			if ( $args['accepted'] == 'pending' ) {
				$where_conditions['accepted'] = "accepted = 0";
			} else if ( $args['accepted'] == 'accepted' ) {
				$where_conditions['accepted'] = "accepted = 1";
			}
		}

		// search_terms
		if ( ! empty( $args['search_terms'] ) ) {
			$search_terms_like = '%' . bp_esc_like( $args['search_terms'] ) . '%';
			$where_conditions['search_terms'] = $wpdb->prepare( "( class LIKE %s )", $search_terms_like, $search_terms_like );
		}

		// Custom WHERE
		if ( ! empty( $where_conditions ) ) {
			$where = 'WHERE ' . implode( ' AND ', $where_conditions );
		}

		return $where;
	}