选择并由多个行值确定

Question

说我有一张桌子的人，一张桌子上的水果和一张桌子都喜欢。

People    fruit    likes 
+-----+--------+ +-----+---------+ +-----+-----+ 
| pid | people | | fid | name | | pid | fid | 
+-----+--------+ +-----+---------+ +-----+-----+ 
| 1 | Mary | | 1 | appple | | 1 | 1 | 
| 2 | Tom | | 2 | orange | | 2 | 1 | 
| 3 | John | | 3 | banana | | 2 | 2 | 
| 4 | George | | 4 | coconut | | 2 | 3 | 
... 

我想打一个查询，可以搜索的人谁喜欢苹果和橘子：

Result 
+----------+--------------- 
| People | likes 
+----------+--------------- 
| Tom  | apple, orange, banana 

其实，我也想知道how to make the same output above but with different conditions说，人们谁喜欢橙色的，但不是苹果或人谁不喜欢香蕉等

Answer 1

SELECT people 
FROM  People 
    JOIN likes USING (pid) 
    JOIN fruit USING (fid) 
GROUP BY pid 

然后：

1. 人谁喜欢苹果和橘子

   HAVING SUM(name='apple') AND SUM(name='orange') 
   

2. 人谁喜欢橙色的，但不是苹果

   HAVING SUM(name='orange') AND NOT SUM(name='apple') 
   

3. 人谁喜欢橙色的，但不是苹果

   HAVING NOT SUM(name='banana') 
   

见他们在sqlfiddle。

Answer 2

SELECT p.people, GROUP_CONCAT(DISTINCT f.name) 
FROM people p INNER JOIN likes l ON p.pid = l.pid 
    INNER JOIN fruit f ON l.fid = f.fid 
WHERE p.id = 2 
GROUP BY p.people