example_.sql

DROP TEMPORARY TABLE IF EXISTS `__ranked_query`;

CREATE TEMPORARY TABLE `__ranked_query` (
  `__object_id` BIGINT UNSIGNED,
  `__rank` BIGINT UNSIGNED,
  KEY `idx_r_o` (`__rank`, `__object_id`),
  KEY `idx_o_r` (`__object_id`, `__rank`)
) engine MEMORY 
AS
SELECT `__object_id`, `__rank` FROM (
  ? --subselect here
) AS `__src_query`;

SET @__prev_id := NULL;
SET @__next_id := NULL;

SET @__obj_rank := (
  SELECT `__rank`
  FROM `__ranked_query`
  WHERE `__object_id` = ? -- ID here
  ORDER BY `__rank` DESC LIMIT 1
);

SET @__prev_id := (
  SELECT `__object_id`
  FROM `__ranked_query` WHERE `__rank` = (@__obj_rank - 1)
);

SET @__next_id := (
  SELECT `__object_id`
  FROM `__ranked_query` WHERE `__rank` = (@__obj_rank + 1)
);

DROP TEMPORARY TABLE `__ranked_query`;

SELECT @__prev_id AS `id_prev`, @__next_id AS `id_next`;