简化MySQL嵌套SELECT

Question

id    title    slug    summary
------------------------------
1     title1   slug1   summary1
2     title2   slug2   summary2
3     title3   slug3   summary3
4     title4   slug4   summary4

我正在尝试选择所有字段,同时选择上一行/下一行的id,title和slug

SELECT
    title, slug, summary, id as current_id,
    (SELECT id    FROM table WHERE id < current_id ORDER BY id DESC LIMIT 1) AS prev_id,
    (SELECT title FROM table WHERE id < current_id ORDER BY id DESC LIMIT 1) AS prev_title,
    (SELECT slug  FROM table WHERE id < current_id ORDER BY id DESC LIMIT 1) AS prev_slug,
    /*
    (SELECT id ...  ) AS next_id
    (SELECT title...) AS next_title
    ...
    and if there are more fields to select, I have to repeat this (SELECT...)
    */
FROM
    table
WHERE
    id IN (2,3,4);

查询有效,但显然这不是明智的方法.

有些人可以帮忙简化一下吗？谢谢

Answer 1

您可以从一个子查询中提取列：

SELECT
    title, slug, summary, id as current_id, prev.prev_id, prev.prev_title, prev.prev_slug, next.next_id, next.next_title, next.next_slug
FROM
    table,
    (SELECT id AS prev_id, title AS prev_title, slug AS prev_slug FROM table WHERE id < 2 ORDER BY id DESC LIMIT 1) AS prev,
    (SELECT id AS next_id, title AS next_title, slug AS next_slug FROM table WHERE id > 2 ORDER BY id DESC LIMIT 1) AS next
WHERE
    id = 2;

IN但如果你必须在 where 中使用子句，这就行不通了；您需要对id...的每个值运行此查询