MySQL似乎并没有正确工作

我有这个大学数据库，我必须检索他们正在教的计算机科学课程，课程（课程编号，部分编号，年，学期）的教师姓名和总数的学生MySQL似乎并没有正确工作

到目前为止，这是管理的内容，但输出不正确。

SELECT i.instructor_id,o.year,o.semester,o.section_number, o.number as CourseNumber,o.Total_num_student 
FROM Instructor i JOIN 
(SELECT t.instructor_id,t.year,t.semester,t.section_number,o1.number,o1.Total_num_student 
FROM teaches t JOIN 
(SELECT COUNT(s.student_id) as Total_num_student,e.section_number,e.number 
    FROM Student s JOIN 
    enrolls e 
    ON s.student_id=e.student_id 
    GROUP BY section_number,e.number) as o1 
ON o1.section_number=t.section_number) as o 
on i.instructor_id=o.instructor_id 
WHERE department='Computer Science';

你能看到输出有什么问题。

create table Course (
    number int, 
    title varchar(255), 
    credits int, 
    syllabus varchar(255), 
PRIMARY KEY (number) 
); 
INSERT INTO Course VALUES (620,'Algorithm',3,'XYZ'); 
INSERT INTO Course VALUES (621,'Algorithm',3,'XYZ'); 
INSERT INTO Course VALUES (232,'Java',2,'ABC'); 
INSERT INTO Course VALUES (420,'Cpp',2,'PQRS'); 
INSERT INTO Course VALUES (720,'Big Data',3,'NVGY'); 
INSERT INTO Course VALUES (120,'Intelligent System',4,'KJHU'); 
INSERT INTO Course VALUES (220,'Operating System',3,'GED'); 
INSERT INTO Course VALUES (480,'Graphics',4,'RSFN'); 
INSERT INTO Course VALUES (520,'Distributed Networks',3,'NHU'); 
INSERT INTO Course VALUES (820,'Data Mining',3,'TYU'); 
INSERT INTO Course VALUES (700,'Cryptography',1,'MNO'); 

create table Student (
    student_id int, 
    name varchar(255), 
    department varchar(255), 
    PRIMARY KEY (student_id) 
); 

INSERT INTO Student VALUES (2345,'Mike','Computer Science'); 
INSERT INTO Student VALUES (346,'Rob','Computer Science'); 
INSERT INTO Student VALUES (789,'Nick','Game Design'); 
INSERT INTO Student VALUES (675,'Sara','Computer Science'); 
INSERT INTO Student VALUES (123,'Raj','Chemical'); 
INSERT INTO Student VALUES (5331,'Jack','Biotech'); 
INSERT INTO Student VALUES (1023,'Michelle','Chemical'); 
INSERT INTO Student VALUES (9800,'Jie','Game Design'); 
INSERT INTO Student VALUES (7834,'Dan','Petroleum'); 
INSERT INTO Student VALUES (4567,'Patrick','Computer Science'); 


create table Instructor (
    instructor_id int, 
    name varchar(255), 
    department varchar(255), 
    title varchar(255), 
    PRIMARY KEY (instructor_id) 
); 


INSERT INTO Instructor VALUES (12,'John','Computer Science','Java'); 
INSERT INTO Instructor VALUES (23,'Bischof','Mechanical','Drawing'); 
INSERT INTO Instructor VALUES (56,'Kwon','Biotech','Biology'); 
INSERT INTO Instructor VALUES (78,'Deever','Security','Cryptography'); 
INSERT INTO Instructor VALUES (45,'Jin','Computer Science','Cpp'); 
INSERT INTO Instructor VALUES (67,'Bailey','Petroleum','Metalurgy'); 
INSERT INTO Instructor VALUES (90,'Richard','Industrial','Manufacture'); 
INSERT INTO Instructor VALUES (11,'Joe','Chemical','Chemistry'); 
INSERT INTO Instructor VALUES (24,'Roger','Game Design','Cpp'); 
INSERT INTO Instructor VALUES (55,'Zack','Computer Science','Design'); 


create table CourseOffering (
    number int, 
    year int, 
    semester int, 
    section_number int, 
    classroom int, 
    PRIMARY KEY (number,year,semester,section_number), 
    FOREIGN KEY (number) REFERENCES Course (number) 
); 

INSERT INTO CourseOffering VALUES (620,2012,2,102,3540); 
INSERT INTO CourseOffering VALUES (621,2013,3,103,3545); 
INSERT INTO CourseOffering VALUES (232,2011,1,103,3455); 
INSERT INTO CourseOffering VALUES (420,2013,3,101,2650); 
INSERT INTO CourseOffering VALUES (720,2013,3,100,3455); 
INSERT INTO CourseOffering VALUES (120,2014,1,102,3000); 
INSERT INTO CourseOffering VALUES (220,2008,2,104,1450); 
INSERT INTO CourseOffering VALUES (480,2009,4,106,1400); 
INSERT INTO CourseOffering VALUES (520,2010,3,102,3500); 
INSERT INTO CourseOffering VALUES (820,2008,3,100,2700); 
INSERT INTO CourseOffering VALUES (700,2012,1,103,2540); 

create table CourseOffering_Timing (
    number int, 
    year int, 
    semester int, 
    section_number int, 
    timing int, 
    PRIMARY KEY (number,year,semester,section_number,timing), 
    FOREIGN KEY (number) REFERENCES Course (number) 
); 

INSERT INTO CourseOffering_Timing VALUES (620,2012,2,102,9); 
INSERT INTO CourseOffering_Timing VALUES (621,2013,3,103,9); 
INSERT INTO CourseOffering_Timing VALUES (232,2011,1,103,3); 
INSERT INTO CourseOffering_Timing VALUES (420,2013,3,101,2); 
INSERT INTO CourseOffering_Timing VALUES (720,2013,3,100,5); 
INSERT INTO CourseOffering_Timing VALUES (120,2014,1,102,4); 
INSERT INTO CourseOffering_Timing VALUES (220,2008,2,104,10); 
INSERT INTO CourseOffering_Timing VALUES (480,2009,4,106,12); 
INSERT INTO CourseOffering_Timing VALUES (520,2010,3,102,4); 
INSERT INTO CourseOffering_Timing VALUES (820,2008,3,100,2); 
INSERT INTO CourseOffering_Timing VALUES (700,2012,1,103,3); 

create table PreRequisite (
    number int, 
    prerequisite_number int, 
    PRIMARY KEY (number,prerequisite_number), 
    FOREIGN KEY (number) REFERENCES Course(number) 
); 

INSERT INTO PreRequisite VALUES (620,480); 
INSERT INTO PreRequisite VALUES (621,481); 
INSERT INTO PreRequisite VALUES (232,120); 
INSERT INTO PreRequisite VALUES (420,320); 
INSERT INTO PreRequisite VALUES (720,580); 
INSERT INTO PreRequisite VALUES (120,110); 
INSERT INTO PreRequisite VALUES (220,130); 
INSERT INTO PreRequisite VALUES (480,380); 
INSERT INTO PreRequisite VALUES (520,360); 
INSERT INTO PreRequisite VALUES (820,700); 
INSERT INTO PreRequisite VALUES (700,610); 


create table enrolls (
    student_id int, 
    number int, 
    year int, 
    semester int, 
    section_number int, 
    grade varchar(10), 
    PRIMARY KEY (student_id,number,year,semester,section_number), 
    FOREIGN KEY (number,year,semester,section_number) REFERENCES CourseOffering(number,year,semester,section_number), 
    FOREIGN KEY (student_id) REFERENCES Student (student_id) 
); 

INSERT INTO enrolls VALUES (2345,620,2012,2,102,'A'); 
INSERT INTO enrolls VALUES (346,232,2011,1,103,'B'); 
INSERT INTO enrolls VALUES (789,420,2013,3,101,'A'); 
INSERT INTO enrolls VALUES (675,621,2013,3,103,'C'); 
INSERT INTO enrolls VALUES (123,120,2014,1,102,'B'); 
INSERT INTO enrolls VALUES (5331,220,2008,2,104,'A'); 
INSERT INTO enrolls VALUES (1023,480,2009,4,106,'B'); 
INSERT INTO enrolls VALUES (9800,520,2010,3,102,'A'); 
INSERT INTO enrolls VALUES (7834,820,2008,3,100,'C'); 
INSERT INTO enrolls VALUES (4567,700,2012,1,103,'F'); 

create table teaches (
    instructor_id int, 
    number int, 
    year int, 
    semester int, 
    section_number int, 
    PRIMARY KEY (instructor_id, number, year, semester, section_number), 
    FOREIGN KEY (instructor_id) REFERENCES Instructor(instructor_id), 
    FOREIGN KEY (number, year, semester, section_number) REFERENCES CourseOffering(number, year, semester, section_number) 
); 



INSERT INTO teaches VALUES (12,620,2012,2,102); 
INSERT INTO teaches VALUES (12,621,2013,3,103); 
INSERT INTO teaches VALUES (23,232,2011,1,103); 
INSERT INTO teaches VALUES (56,420,2013,3,101); 
INSERT INTO teaches VALUES (78,720,2013,3,100); 
INSERT INTO teaches VALUES (45,120,2014,1,102); 
INSERT INTO teaches VALUES (67,220,2008,2,104); 
INSERT INTO teaches VALUES (90,480,2009,4,106); 
INSERT INTO teaches VALUES (11,520,2010,3,102); 
INSERT INTO teaches VALUES (24,820,2008,3,100); 
INSERT INTO teaches VALUES (55,700,2012,1,103);

来源

2014-03-03 user3342812

你能给你想要的结果表格格式吗？ –

以表格格式提供期望的输出将使其更容易。 – Joshi

看看这会为你

SELECT Instructor.name AS instructor_name, teaches.section_number AS section_number, 
teaches.year AS year, teaches.semester AS semester, COUNT(enrolls.student_id) FROM Instructor 
INNER JOIN teaches ON teaches.instructor_id = Instructor.instructor_id 
INNER JOIN enrolls ON teaches.section_number = enrolls.section_number AND teaches.semester = enrolls.semester AND teaches.year = enrolls.year 
WHERE department='Computer Science' 
GROUP BY Instructor.name, teaches.section_number, teaches.year, teaches.semester;

来源

2014-03-03 02:54:56 usha

http://sqlfiddle.com/#!2/fd51de/21 学生总人数为3人。根据数据库不应该是1吗？ – user3342812

@ user3342812：立即尝试 – usha

工作，我不能完全确定你想要达到的，但是这是如果你想保留的部分信息：

SELECT a.instructor_id, group_concat(DISTINCT a.year SEPARATOR ', ') YEAR, group_concat(DISTINCT a.semester SEPARATOR ', ') SEMESTER, group_concat(DISTINCT a.section_number SEPARATOR ', ') SECTION_NUMBER, group_concat(DISTINCT a.coursenumber SEPARATOR ', ') COURSENUMBER, count(a.student_id) as Total_num_student FROM (
SELECT e.student_id, i.instructor_id, t.year,t.semester,t.section_number, t.number as CourseNumber 
FROM instructor i 
JOIN teaches t 
ON i.instructor_id = t.instructor_id 
JOIN enrolls e 
ON e.section_number=t.section_number 
WHERE department='Computer Science') a 
GROUP BY a.instructor_id 
; 


SELECT a.instructor_id, a.year, a.semester, a.section_number, a.coursenumber, count(a.student_id) as Total_num_student FROM (
SELECT e.student_id, i.instructor_id, t.year,t.semester,t.section_number, t.number as CourseNumber 
FROM instructor i 
JOIN teaches t 
ON i.instructor_id = t.instructor_id 
JOIN enrolls e 
ON e.section_number=t.section_number 
WHERE department='Computer Science') a 
GROUP BY a.instructor_id, a.section_number 
;

SQLFiddle demo

来源

2014-03-03 03:41:41

MySQL似乎并没有正确工作

回答

相关问题