符合幾個條件中選擇行

Question

我有一個表pupil_teachers像這樣

+------+----------+------------+ 
| id | pupil_id | teacher_id | 
+------+----------+------------+ 
| 1 | 100  | 200  | 
| 2 | 101  | 200  | 
| 3 | 102  | 200  | 
| 4 | 102  | 201  | 
| 5 | 101  | 201  | 
| 6 | 101  | 202  | 
| 7 | 103  | 200  | 
+------+----------+------------+ 

查詢將檢索小學生100，101和102有共同的所有教師。所以在這種情況下，它只會是老師ID 200

瞳孔103也有老師ID 200，而不是查詢的一部分，我只是想查詢學生100，101和102

所以它將開始於：

SELECT teacher_id 
FROM pupil_teachers 
WHERE 

我真的不知道下一步該去哪裏。顯然，以下說法不正確

SELECT teacher_id 
FROM pupil_teachers 
WHERE pupil_id IN (100, 101, 102) 

Answer 1

這裏使用Group By和Having條款

SELECT teacher_id 
FROM pupil_teachers 
WHERE pupil_id IN (100, 101, 102) 
Group by teacher_id 
Having Count(Distinct pupil_id) = 3 

另一種方式

SELECT teacher_id 
FROM pupil_teachers 
Group by teacher_id 
Having Count(Case when pupil_id = 100 then 1 end) > 0 
    AND Count(Case when pupil_id = 101 then 1 end) > 0 
    AND Count(Case when pupil_id = 102 then 1 end) > 0