Question

所以我进入了这个子查询

SELECT movies.movieID, movies.user 
FROM movies
WHERE movies.user IN(Select movies.user 
                     FROM movies 
                     WHERE movies.movieID = '19') 
AND movies.movieID <> (SELECT movies.movieID 
                           FROM movies 
                           WHERE movies.user='5'
                           AND movies.movieID = '19') 
AND movies.movieID <> '19'

它给了我这个结果

--------------------------
|  movieID    | user     |
--------------------------
|    20       |   4      |
--------------------------
|    21       |   4      |
--------------------------
|    22       |   5      |
--------------------------
|    23       |   4      |
--------------------------

如何摆脱用户5的任何结果？

我认为问题出在

AND movies.movieID <> (SELECT movies.movieID 
                           FROM movies 
                           WHERE movies.user='5'
                           AND movies.movieID = '19')

但是当我尝试单独运行查询时

SELECT movies.movieID 
FROM movies 
WHERE movies.user='5'
AND movies.movieID = '19'

它只给出了2个结果，只有19，不返回movieID 22。此查询的结果是正确的。为什么在子查询中运行它时会返回22？

是的，有人可以帮帮我吗？感谢

Answer 1

如果您不想使用user = 5的记录，则只需添加

AND movies.user <> '5'

您的子查询

SELECT movies.movieID 
FROM movies 
WHERE movies.user='5'
AND movies.movieID = '19'

说，选择movieID为19且用户为5的movieID。此查询将返回19.

所以这个

AND movies.movieID <> (SELECT movies.movieID 
                       FROM movies 
                       WHERE movies.user='5'
                       AND movies.movieID = '19')

说我不想要movieID = 19，这就是为什么在你的最终查询中你仍然可以得到movieID = 5的记录。

Answer 2

使用user ='5'过滤掉记录的子句只过滤掉user ='5'和movieID ='19'的记录

AND movies.movieID <> (SELECT movies.movieID 
                           FROM movies 
                           WHERE movies.user='5'
                           AND movies.movieID = '19')

这意味着它没有过滤掉user ='5'和movieID = '22'的记录

根据您的需要，您可以尝试：

AND movies.movieID <> (SELECT movies.movieID 
                           FROM movies 
                           WHERE movies.user='5'
                           OR movies.movieID = '19')

或只在主AND user != 5子句

上添加WHERE

SELECT movies.movieID, movies.user 
FROM movies
WHERE movies.user IN(Select movies.user 
                     FROM movies 
                     WHERE movies.movieID = '19') 
AND movies.movieID <> (SELECT movies.movieID 
                           FROM movies 
                           WHERE movies.user='5'
                           AND movies.movieID = '19') 
AND movies.movieID <> '19'
AND user <> '5'

MySQL子查询不需要的结果

2 个答案: