從表中選擇A列或B列中的值

Question

我正在處理電影數據庫，並且有一個鏈接表，因此可以將電影鏈接到其續集。 我已經編寫了以下查詢，以便可以返回鏈接表的任何列中的movie_id所在的續集列表，但是我想知道是否還有更好的方法可以這樣做，因為這似乎是一個漫長的過程打算嗎？

SELECT movie_id, movie_title FROM movies WHERE movie_id in 
    (SELECT movie_1 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_2 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_3 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_4 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_5 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_6 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_7 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_8 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_9 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1)
or movie_id in 
    (SELECT movie_10 FROM lk_movies WHERE movie_1 = 1  or  movie_2 = 1 or  movie_3 = 1 or movie_4 = 1 or movie_5 = 1 or movie_6 = 1 or movie_7 = 1 or movie_8 = 1 or movie_9 = 1 or movie_10 = 1);

Answer 1

不幸的是， Mysql不支持Unpivot或Cross Apply運算符，因此這是我想出的最好的方法

子查詢

SELECT movie_1 
FROM   lk_movies 
WHERE  movie_1 = 1 
        OR movie_2 = 1 
        OR movie_3 = 1 
        OR movie_4 = 1 
        OR movie_5 = 1 
        OR movie_6 = 1 
        OR movie_7 = 1 
        OR movie_8 = 1 
        OR movie_9 = 1 
        OR movie_10 = 1 

可以通過反轉IN運算符來重寫

SELECT movie_10 
FROM   lk_movies 
WHERE  1 IN( movie_1, movie_2, movie_3, movie_4, 
             movie_5, movie_6, movie_7, movie_8, 
             movie_9, movie_10 ) 

然后使用Union all而不是多個OR條件，這是完整的查詢

 SELECT movie_id, 
       movie_title 
FROM   movies 
WHERE  movie_id IN (SELECT movie_1 
                    FROM   lk_movies 
                    WHERE  1 IN( movie_1, movie_2, movie_3, movie_4, 
                                 movie_5, movie_6, movie_7, movie_8, 
                                 movie_9, movie_10 ) 
                    UNION ALL 
                    SELECT movie_2 
                    FROM   lk_movies 
                    WHERE  1 IN( movie_1, movie_2, movie_3, movie_4, 
                                 movie_5, movie_6, movie_7, movie_8, 
                                 movie_9, movie_10 ) 
                    UNION ALL 
                    ...............
                    ...............
                    SELECT movie_10 
                    FROM   lk_movies 
                    WHERE  1 IN( movie_1, movie_2, movie_3, movie_4, 
                                 movie_5, movie_6, movie_7, movie_8, 
                                 movie_9, movie_10 )) 

Answer 2

當您創建帶有附加數字的列的表時，幾乎可以肯定您做錯了。 您的表未正確規范化 。

下面的所有代碼未經測試，因為我不使用mysql。 它可能有一些語法錯誤，但是您應該了解一下。

您可以創建一個這樣的表：

CREATE TABLE Movie
| ID | Title   | ... | Sequel |
|  1 | Shrek   | ... | 2      |
|  2 | Shrek 2 | ... | 3      |
|  3 | Shrek 3 | ... | NULL   |

這樣，您將只知道下一個續集，並且必須必須遵循Sequel列並指向下一個ID，直到您在Sequel到達具有NULL的Movie為止。

SELECT A.Titel, B.Titel AS Sequel
FROM Movie A
INNER JOIN Movie B
ON A.Sequel = B.ID

要在一個查詢中查找所有續集，請為該續集考慮一個單獨的表。 這也消除了對續集數量的限制。

Movie
| ID | Title    | ... |
|  1 | Shrek    | ... |
|  2 | Shrek 2  | ... |
|  3 | Shrek 3  | ... |

和

Sequel
| Movie_ID | Sequel_ID |
|        1 |         2 | 
|        1 |         3 |
|        2 |         3 |

然后您可以從中選擇

SELECT Movie.Titel 
FROM Movie 
INNER JOIN Sequel
ON Movie.Movie_ID = Sequel.Sequel_ID
INNER JOIN Movie S
ON Sequel.Sequel_ID = S.Movie_ID

此處的缺點是您復制信息，即，您需要為Shrek存儲有Shrek 2和Shrek 3作為續集，而對於Shrek 2，您需要復制Shrek 3是Shrek 2的續集這一事實。 ，您總是只想從第一部電影中搜索。

請注意漢蘭達的特殊情況，它不能有后遺症。 只可以有一個人。