Question

我只想选择没有产品ID为11的行的学生ID。但我不能。我该怎么办？

BEGIN TRANSACTION;
CREATE TABLE STUDENTS(Id integer PRIMARY KEY, name text,year_born integer 
);

CREATE TABLE PROJECT(project_id integer,title text,project_owner 
text,year_written integer );

CREATE TABLE PROJECTWORKS(student_id integer,project_id integer);
INSERT INTO STUDENTS VALUES(1598,'james',1996);
INSERT INTO STUDENTS VALUES(2479,'andre',1996);
INSERT INTO STUDENTS VALUES(3682,'pierre',1997);


INSERT INTO PROJECT VALUES(10,'A','ABC',2008);
INSERT INTO PROJECT VALUES(11,'B','ABC',2010);
INSERT INTO PROJECT VALUES(12,'C','ABC',2016);
INSERT INTO PROJECT VALUES(13,'D','CBA',2014);


INSERT INTO PROJECTWORKS VALUES(1598,10);
INSERT INTO PROJECTWORKS VALUES(1598,11);
INSERT INTO PROJECTWORKS VALUES(1598,12);
INSERT INTO PROJECTWORKS VALUES(3682,12);
INSERT INTO PROJECTWORKS VALUES(3682,13);
INSERT INTO PROJECTWORKS VALUES(2479,12);

SELECT * FROM STUDENTS;
SELECT * FROM PROJECT;
SELECT * FROM PROJECTWORKS;

SELECT DISTINCT student_id FROM PROJECTWORKS
WHERE not project_id=11 and (project_id=10 OR project_id=12 OR 
project_id=13);

我只想 3682 和 2479 因为 1598 有11个。

Answer 1

NOT EXISTS非常适合：

SELECT DISTINCT student_id
FROM PROJECTWORKS p
WHERE project_id IN (10, 12, 13)
AND NOT EXISTS
(SELECT 1
 FROM PROJECTWORKS p2
 WHERE p.student_id = p2.student_id
 AND p2.project_id = 11);

此外，我认为你的意思是你不想要ID 11，因为我在你的例子中没有看到14。

Answer 2

如果我理解你，这就是你想要的

[System.Byte[]]::CreateInstance(<Length>)

Answer 3

您可以在两个结果之间使用连接

 select distinct student_id
 from PROJECTWORKS  p
 where  project_id NOT IN (11) 
 INNER JOIN  (
     Select distinct student_id
     from PROJECTWORKS 
     where  project_id IN ( 10, 12, 13)
 ) T on t.student_id = p.student_id

Answer 4

SELECT DISTINCT student_id FROM PROJECTWORKS
WHERE student_id not in
(select student_id from PROJECTWORKS where project_id=11)

你的问题不明确。上面的代码片段用于不同的student_id，其中没有project_id为11

mysql选择不起作用

4 个答案: