Question

好的，我有一张桌子，里面有学生证和课程。比如

00001 CS-543
00001 CS-145
00002 HIST-123
... etc.

我有一些课程ID列;我们称之为B，

CS-123
... etc.

我想搜索所有参加B课程的学生。我怎么能为此写一个查询？

Answer 1

SELECT A.StudentID
FROM A
  INNER JOIN B ON A.CourseID = B.CourseID
GROUP BY A.StudentID
HAVING COUNT(DISTINCT A.CourseID) >= COUNT(DISTINCT B.CourseID)

Answer 2

SELECT DISTINCT STUDENT FROM A WHERE STUDENT NOT IN
(
  SELECT STUDENT FROM
  (
    SELECT *
    FROM 
     (SELECT DISTINCT STUDENT FROM A) AS ALLSTUDENTS 
     CROSS JOIN B  
    EXCEPT 
    SELECT * FROM A
  ) AS INCOMPLETE
)

Answer 3

使用IN子句：

SELECT * FROM B WHERE B.CourseID IN (SELECT CourseID FROM A)

这将为您提供B中出现在A

中的所有记录

SQL在另一个表中查找列的所有值

3 个答案: