使用2个表中的字段对UNION进行排序

Question

我正在尝试从表NEWS和EVENTS中选择即将发生的事件和最新消息，并按NEWS.timestamp和EVENT.datetime订购

基本的非有序查询如下：

SELECT event_id, title FROM events
UNION
SELECT news_id, subject FROM news

Answer 1

将每个列添加到您的选择列表中，每个列的名称别名相同。然后只在底部ORDER BY。

SELECT
  event_id,
  title,
  datetime AS thedate
FROM events
UNION
SELECT
  news_id,
  subject,
  timestamp AS thedate
FROM news
ORDER BY thedate

Answer 2

迈克尔答案的一个小变化（如果您想按时间戳和日期时间排序但不显示它们）：

  SELECT
    event_id,
    title
  FROM 
    ( SELECT
        event_id,
        title,
        datetime AS thedate
      FROM events
    UNION ALL
      SELECT
        news_id,
        subject,
        timestamp AS thedate
      FROM news
    ) AS tmp
  ORDER BY thedate