protected function get_items_query_where() {
		global $wpdb;

		$where_conditions = array();
		$where_values     = array();
		if ( ! empty( $_REQUEST['level'] ) && WC_Log_Levels::is_valid_level( $_REQUEST['level'] ) ) {
			$where_conditions[] = 'level >= %d';
			$where_values[]     = WC_Log_Levels::get_level_severity( $_REQUEST['level'] );
		}
		if ( ! empty( $_REQUEST['source'] ) ) {
			$where_conditions[] = 'source = %s';
			$where_values[]     = wc_clean( $_REQUEST['source'] );
		}
		if ( ! empty( $_REQUEST['s'] ) ) {
			$where_conditions[] = 'message like %s';
			$where_values[]     = '%' . $wpdb->esc_like( wc_clean( wp_unslash( $_REQUEST['s'] ) ) ) . '%';
		}

		if ( empty( $where_conditions ) ) {
			return '';
		}

		return $wpdb->prepare( 'WHERE 1 = 1 AND ' . implode( ' AND ', $where_conditions ), $where_values );
	}