哪种方法更有效地从许多表中收集结果？

Question

最好像二十个单独的查询，如SELECT id FROM table WHERE value = 'hello'，然后将所有内容组合在一个单一的1维数组中，或者像一个巨大的查询，如

SELECT `t1`.`id` FROM (SELECT `id` FROM `table` WHERE `value` = 'hello') AS `t1`
LEFT JOIN (SELECT `id` FROM `table` WHERE `value` = 'world') AS `t2`
ON `t1`.`id` = `t2`.`id`
...
UNION ALL
SELECT `t1`.`id` FROM (SELECT `id` FROM `table` WHERE `value` = 'hello') AS `t1`
RIGHT JOIN (SELECT `id` FROM `table` WHERE `value` = 'world') AS `t2`
ON `t1`.`id` = `t2`.`id`
...

依此类推，直到我成功加入所有二十个来源的结果？