mysql查询从多个中选择,按日期排序

Question

从多个表中选择并按日期排序所有内容,从最新到最旧,这是一种简单明了的方法吗？

 mysql_query("
               SELECT * 
               FROM posts, comments, photos 
               WHERE userID='$session' 
               ORDER BY date");

如果我想做那样的事情.

Answer 1

SELECT *
FROM (SELECT userID, Col1, Col2, Col3, date
      FROM posts
      UNION
      SELECT userID, Col1, Col2, Col3, date
      FROM comments
      SELECT userID, Col1, Col2, Col3, date
      FROM photos ) t
WHERE userID = 123
ORDER BY date DESC