結合兩個查詢OR和LEFT加入 - MySQL

Question

我遇到了MySQL查詢問題（我是一個新手，所以對我來說很容易！）。我有一個帶有電視節目的網站，並希望根據兩種不同的操作（用於自定義時間表）選擇兩個日期之間播出的節目（沒有問題）。基本上，如果用戶正在跟隨（uses_follow_shows）或觀看節目（user_watched），我想要顯示該節目，所以我認爲我會在下面有類似的內容，但這不起作用。它工作正常，除了我的結果有一方面的查詢結果和另一方的結果。

即：

name     a1 name   a 
    Mistresses (US)  2 Wilfred (US) 2 
    Mistresses (US)  2 Dexter   2 

這是我的查詢：

我怎樣才能使它所以我所有的名字都在同一列？

 SELECT * FROM (
     SELECT shows.name, users_follow_shows.user_id a1 
     FROM show_episode_airdate join 
      show_episode 
      on show_episode.episode_id = show_episode_airdate.episode_id join 
      shows 
      on shows.imdb_id = show_episode.imdb_id_show join 
      show_network 
      on show_network.show_id = shows.id join 
      network 
      on show_network.network_id = network.network_id join 
      users_follow_shows 
      on shows.id = users_follow_shows.show_id 

     WHERE show_episode_airdate.airdate BETWEEN '2013-07-20' AND '2013-07-27' and 
      users_follow_shows.user_id = 2 

     ORDER by network.network_id ASC) a1 

     JOIN (
     SELECT shows.name, user_watched.user_id a 
     FROM show_episode_airdate join 
      show_episode 
      on show_episode.episode_id = show_episode_airdate.episode_id join 
      shows 
      on shows.imdb_id = show_episode.imdb_id_show join 
      show_network 
      on show_network.show_id = shows.id join 
      network 
      on show_network.network_id = network.network_id join 
      user_watched 
      on shows.id = user_watched.show_id 

     WHERE show_episode_airdate.airdate BETWEEN '2013-07-20' AND '2013-07-27' and 
      user_watched.user_id = 2 

     ORDER by network.network_id ASC) a 

     ON a = a1 

任何幫助表示讚賞。謝謝。

Answer 1

未經測試，但我會簡化你這樣的查詢：

SELECT 
    shows.name, 
    users_follow_shows.user_id a1 
FROM show_episode_airdate 
    JOIN show_episode on show_episode.episode_id = show_episode_airdate.episode_id 
    JOIN shows on shows.imdb_id = show_episode.imdb_id_show 
    JOIN show_network on show_network.show_id = shows.id 
    JOIN network on show_network.network_id = network.network_id 
    LEFT JOIN users_follow_shows on shows.id = users_follow_shows.show_id 
    LEFT JOIN user_watched on shows.id = user_watched.show_id 
WHERE show_episode_airdate.airdate BETWEEN '2013-07-20' AND '2013-07-27' 
    AND (users_follow_shows.user_id = 2 OR user_watched.user_id = 2) 

Answer 2

你不應該使用JOIN。你正在尋找的是一個UNION：

http://dev.mysql.com/doc/refman/5.0/en/union.html

Answer 3

你可以像這樣子查詢開始：

SELECT DISTINCT user_id, show_id 
    FROM (
    SELECT user_id 
      show_id 
     FROM user_watched 
    UNION 
    SELECT user_id 
      show_id 
     FROM user_follows_show 
) 

這會給你一個獨特的用戶和節目的虛表，以滿足你的兩個將它們包含在列表中的標準。然後，您可以加入到你的查詢的其餘部分，像這樣：

SELECT whatever 
    FROM whatever 
    JOIN (
    SELECT DISTINCT user_id, show_id 
     FROM (
     SELECT user_id 
       show_id 
      FROM user_watched 
     UNION 
     SELECT user_id 
       show_id 
      FROM user_follows_show 
    ) USER_INTERESTED ON USER_INTERESTED.show_id = shows.id 
    WHERE whatever 

的技巧是使用結構化查詢語言的結構部分獲得用戶之間的虛擬關係/顯示您需要的請求你的查詢。