SQL查询课程，学期和学生
嗨，我有一个看起来像这样的架构
我正尝试进行这3个查询
-
找到教授最多数量的不同课程的前4名教师的姓名。同时显示所教课程的总数。
输出列：InstructorName，NumberOfCoursesTaught
排序方式：NumberOfCourses按降序排列
-
找到开设课程最多的前3个学期。 （将2009年春季和2010年春季划分为两个不同的学期。
输出列：学期，年份，课程数
排序方式：NumberOfCourses降序
-
找到参加课程最多的前2名学生。
输出列：S_ID，StudentName，NumberOfCourses
排序方式：NumberOfCourses降序
对于查询1，我写了
Select name AS InstructorName, count(course_id) AS NumberOfCourses
from Teaches where name IN
(SELECT name FROM Instructor where Instructor.i_id = Teaches.i_id)
group by i_id
order by count(course_id) DESC;
对于查询2
SELECT semester, year, count(course_id) as
NumberOfCourses from Takes WHERE year='2009'
group by semester, year
order by count(course_id) DESC;
对于查询3
SELECT s_id as S_ID, name as StudentName, count(course_id) as NumberOfCourses
FROM Takes where name IN
(SELECT name from Student where Takes.s_id = Student.s_id)
group by s_id
order by count(course_id) DESC;
查询1和3给出错误
ORA-00904: "NAME": invalid identifier
查询2提供了输出，但这是错误的。我需要帮助使3个查询正确无误
测试数据为 表格文件是
create table classroom (building varchar(15), room_number varchar(7), capacity numeric(4,0), primary key (building, room_number));
create table department (dept_name varchar(20), building varchar(15), budget numeric(12,2) check (budget > 0), primary key (dept_name));
create table course (course_id varchar(8), title varchar(50), dept_name varchar(20), credits numeric(2,0) check (credits > 0),
primary key(course_id));
create table instructor (i_ID varchar(5), name varchar(20) not null, dept_name varchar(20), salary numeric(8,2) check (salary > 29000), primary key (i_ID));
create table section (course_id varchar(8), sec_id varchar(8), semester varchar(6) check (semester in ('Fall', 'Winter', 'Spring', 'Summer')), year numeric(4,0) check (year > 1701 and year < 2100), building varchar(15), room_number varchar(7), time_slot_id varchar(4), primary key (course_id, sec_id, semester, year));
create table teaches (i_ID varchar(5), course_id varchar(8), sec_id varchar(8), semester varchar(6), year numeric(4,0), primary key (i_ID, course_id, sec_id, semester, year));
create table student (s_ID varchar(5), name varchar(20) not null, dept_name varchar(20), tot_cred numeric(3,0) check (tot_cred >= 0), primary key (s_ID));
create table takes (s_ID varchar(5), course_id varchar(8), sec_id varchar(8), semester varchar(6), year numeric(4,0), grade varchar(2), primary key (s_ID, course_id, sec_id, semester, year));
create table advisor (s_ID varchar(5), i_ID varchar(5), primary key (s_ID));
create table time_slot (time_slot_id varchar(4), day varchar(1),start_hr numeric(2) check (start_hr >= 0 and start_hr < 24), start_min numeric(2) check (start_min >= 0 and start_min < 60), end_hr numeric(2) check (end_hr >= 0 and end_hr < 24), end_min numeric(2) check(end_min >= 0 and end_min < 60), primary key (time_slot_id, day, start_hr, start_min));
create table prereq (course_id varchar(8), prereq_id varchar(8), primary key (course_id, prereq_id));
create table grade_points(grade varchar(2), points Number(10,4), primary key (grade));
数据文件为
delete from prereq;
delete from time_slot;
delete from advisor;
delete from takes;
delete from student;
delete from teaches;
delete from section;
delete from instructor;
delete from course;
delete from department;
delete from classroom;
-- Classroom
insert into classroom values ('Packard', '101', '500');
insert into classroom values ('Painter', '514', '10');
insert into classroom values ('Taylor', '3128', '70');
insert into classroom values ('Watson', '100', '30');
insert into classroom values ('Watson', '120', '50');
-- Department
insert into department values ('Biology', 'Watson', '90000');
insert into department values ('Comp. Sci.', 'Taylor', '100000');
insert into department values ('Elec. Eng.', 'Taylor', '85000');
insert into department values ('Finance', 'Painter', '120000');
insert into department values ('History', 'Painter', '50000');
insert into department values ('Music', 'Packard', '80000');
insert into department values ('Physics', 'Watson', '70000');
-- Course
insert into course values ('BIO-101', 'Intro. to Biology', 'Biology', '4');
insert into course values ('BIO-301', 'Genetics', 'Biology', '4');
insert into course values ('BIO-399', 'Computational Biology', 'Biology', '3');
insert into course values ('CS-101', 'Intro. to Computer Science', 'Comp. Sci.', '4');
insert into course values ('CS-190', 'Game Design', 'Comp. Sci.', '4');
insert into course values ('CS-315', 'Robotics', 'Comp. Sci.', '3');
insert into course values ('CS-319', 'Image Processing', 'Comp. Sci.', '3');
insert into course values ('CS-347', 'Database System Concepts', 'Comp. Sci.', '3');
insert into course values ('EE-181', 'Intro. to Digital Systems', 'Elec. Eng.', '3');
insert into course values ('FIN-201', 'Investment Banking', 'Finance', '3');
insert into course values ('HIS-351', 'World History', 'History', '3');
insert into course values ('MU-199', 'Music Video Production', 'Music', '3');
insert into course values ('PHY-101', 'Physical Principles', 'Physics', '4');
-- Instructor
insert into instructor values ('10101', 'Srinivasan', 'Comp. Sci.', '65000');
insert into instructor values ('12121', 'Wu', 'Finance', '90000');
insert into instructor values ('15151', 'Mozart', 'Music', '40000');
insert into instructor values ('22222', 'Einstein', 'Physics', '95000');
insert into instructor values ('32343', 'El Said', 'History', '60000');
insert into instructor values ('33456', 'Gold', 'Physics', '87000');
insert into instructor values ('45565', 'Katz', 'Comp. Sci.', '75000');
insert into instructor values ('58583', 'Califieri', 'History', '62000');
insert into instructor values ('76543', 'Singh', 'Finance', '80000');
insert into instructor values ('76766', 'Crick', 'Biology', '72000');
insert into instructor values ('83821', 'Brandt', 'Comp. Sci.', '92000');
insert into instructor values ('98345', 'Kim', 'Elec. Eng.', '80000');
-- Section
insert into section values ('BIO-101', '1', 'Summer', '2009', 'Painter', '514', 'B');
insert into section values ('BIO-301', '1', 'Summer', '2010', 'Painter', '514', 'A');
insert into section values ('CS-101', '1', 'Fall', '2009', 'Packard', '101', 'H');
insert into section values ('CS-101', '1', 'Spring', '2010', 'Packard', '101', 'F');
insert into section values ('CS-190', '1', 'Spring', '2009', 'Taylor', '3128', 'E');
insert into section values ('CS-190', '2', 'Spring', '2009', 'Taylor', '3128', 'A');
insert into section values ('CS-315', '1', 'Spring', '2010', 'Watson', '120', 'D');
insert into section values ('CS-319', '1', 'Spring', '2010', 'Watson', '100', 'B');
insert into section values ('CS-319', '2', 'Spring', '2010', 'Taylor', '3128', 'C');
insert into section values ('CS-347', '1', 'Fall', '2009', 'Taylor', '3128', 'A');
insert into section values ('EE-181', '1', 'Spring', '2009', 'Taylor', '3128', 'C');
insert into section values ('FIN-201', '1', 'Spring', '2010', 'Packard', '101', 'B');
insert into section values ('HIS-351', '1', 'Spring', '2010', 'Painter', '514', 'C');
insert into section values ('MU-199', '1', 'Spring', '2010', 'Packard', '101', 'D');
insert into section values ('PHY-101', '1', 'Fall', '2009', 'Watson', '100', 'A');
-- Teaches
insert into teaches values ('10101', 'CS-101', '1', 'Fall', '2009');
insert into teaches values ('10101', 'CS-315', '1', 'Spring', '2010');
insert into teaches values ('10101', 'CS-347', '1', 'Fall', '2009');
insert into teaches values ('12121', 'FIN-201', '1', 'Spring', '2010');
insert into teaches values ('15151', 'MU-199', '1', 'Spring', '2010');
insert into teaches values ('22222', 'PHY-101', '1', 'Fall', '2009');
insert into teaches values ('32343', 'HIS-351', '1', 'Spring', '2010');
insert into teaches values ('45565', 'CS-101', '1', 'Spring', '2010');
insert into teaches values ('45565', 'CS-319', '1', 'Spring', '2010');
insert into teaches values ('76766', 'BIO-101', '1', 'Summer', '2009');
insert into teaches values ('76766', 'BIO-301', '1', 'Summer', '2010');
insert into teaches values ('83821', 'CS-190', '1', 'Spring', '2009');
insert into teaches values ('83821', 'CS-190', '2', 'Spring', '2009');
insert into teaches values ('83821', 'CS-319', '2', 'Spring', '2010');
insert into teaches values ('98345', 'EE-181', '1', 'Spring', '2009');
-- Student
insert into student values ('00128', 'Zhang', 'Comp. Sci.', '102');
insert into student values ('12345', 'Shankar', 'Comp. Sci.', '32');
insert into student values ('19991', 'Brandt', 'History', '80');
insert into student values ('23121', 'Chavez', 'Finance', '110');
insert into student values ('44553', 'Peltier', 'Physics', '56');
insert into student values ('45678', 'Levy', 'Physics', '46');
insert into student values ('54321', 'Williams', 'Comp. Sci.', '54');
insert into student values ('55739', 'Sanchez', 'Music', '38');
insert into student values ('70557', 'Snow', 'Physics', '0');
insert into student values ('76543', 'Brown', 'Comp. Sci.', '58');
insert into student values ('76653', 'Aoi', 'Elec. Eng.', '60');
insert into student values ('98765', 'Bourikas', 'Elec. Eng.', '98');
insert into student values ('98988', 'Tanaka', 'Biology', '120');
-- Takes
insert into takes values ('00128', 'CS-101', '1', 'Fall', '2009', 'A');
insert into takes values ('00128', 'CS-347', '1', 'Fall', '2009', 'A-');
insert into takes values ('12345', 'CS-101', '1', 'Fall', '2009', 'C');
insert into takes values ('12345', 'CS-190', '2', 'Spring', '2009', 'A');
insert into takes values ('12345', 'CS-315', '1', 'Spring', '2010', 'A');
insert into takes values ('12345', 'CS-347', '1', 'Fall', '2009', 'A');
insert into takes values ('19991', 'HIS-351', '1', 'Spring', '2010', 'B');
insert into takes values ('23121', 'FIN-201', '1', 'Spring', '2010', 'C+');
insert into takes values ('44553', 'PHY-101', '1', 'Fall', '2009', 'B-');
insert into takes values ('45678', 'CS-101', '1', 'Fall', '2009', 'F');
insert into takes values ('45678', 'CS-101', '1', 'Spring', '2010', 'B+');
insert into takes values ('45678', 'CS-319', '1', 'Spring', '2010', 'B');
insert into takes values ('54321', 'CS-101', '1', 'Fall', '2009', 'A-');
insert into takes values ('54321', 'CS-190', '2', 'Spring', '2009', 'B+');
insert into takes values ('55739', 'MU-199', '1', 'Spring', '2010', 'A-');
insert into takes values ('76543', 'CS-101', '1', 'Fall', '2009', 'A');
insert into takes values ('76543', 'CS-319', '2', 'Spring', '2010', 'A');
insert into takes values ('76653', 'EE-181', '1', 'Spring', '2009', 'C');
insert into takes values ('98765', 'CS-101', '1', 'Fall', '2009', 'C-');
insert into takes values ('98765', 'CS-315', '1', 'Spring', '2010', 'B');
insert into takes values ('98988', 'BIO-101', '1', 'Summer', '2009', 'A');
insert into takes values ('98988', 'BIO-301', '1', 'Summer', '2010', null);
-- Advisor
insert into advisor values ('00128', '45565');
insert into advisor values ('12345', '10101');
insert into advisor values ('23121', '76543');
insert into advisor values ('44553', '22222');
insert into advisor values ('45678', '22222');
insert into advisor values ('76543', '45565');
insert into advisor values ('76653', '98345');
insert into advisor values ('98765', '98345');
insert into advisor values ('98988', '76766');
-- Time_slot
insert into time_slot values ('A', 'M', '8', '0', '8', '50');
insert into time_slot values ('A', 'W', '8', '0', '8', '50');
insert into time_slot values ('A', 'F', '8', '0', '8', '50');
insert into time_slot values ('B', 'M', '9', '0', '9', '50');
insert into time_slot values ('B', 'W', '9', '0', '9', '50');
insert into time_slot values ('B', 'F', '9', '0', '9', '50');
insert into time_slot values ('C', 'M', '11', '0', '11', '50');
insert into time_slot values ('C', 'W', '11', '0', '11', '50');
insert into time_slot values ('C', 'F', '11', '0', '11', '50');
insert into time_slot values ('D', 'M', '13', '0', '13', '50');
insert into time_slot values ('D', 'W', '13', '0', '13', '50');
insert into time_slot values ('D', 'F', '13', '0', '13', '50');
insert into time_slot values ('E', 'T', '10', '30', '11', '45 ');
insert into time_slot values ('E', 'R', '10', '30', '11', '45 ');
insert into time_slot values ('F', 'T', '14', '30', '15', '45 ');
insert into time_slot values ('F', 'R', '14', '30', '15', '45 ');
insert into time_slot values ('G', 'M', '16', '0', '16', '50');
insert into time_slot values ('G', 'W', '16', '0', '16', '50');
insert into time_slot values ('G', 'F', '16', '0', '16', '50');
insert into time_slot values ('H', 'W', '10', '0', '12', '30');
-- Prereq
insert into prereq values ('BIO-301', 'BIO-101');
insert into prereq values ('BIO-399', 'BIO-101');
insert into prereq values ('CS-190', 'CS-101');
insert into prereq values ('CS-315', 'CS-101');
insert into prereq values ('CS-319', 'CS-101');
insert into prereq values ('CS-347', 'CS-101');
insert into prereq values ('EE-181', 'PHY-101');
-- Grade_points
insert into grade_points values ('A+', 4.0);
insert into grade_points values ('A', 4.0);
insert into grade_points values ('A-', 3.7);
insert into grade_points values ('B+', 3.3);
insert into grade_points values ('B', 3.0);
insert into grade_points values ('B-', 2.7);
insert into grade_points values ('C+', 2.3);
insert into grade_points values ('C', 2.0);
insert into grade_points values ('C-', 1.7);
insert into grade_points values ('D+', 1.3);
insert into grade_points values ('D', 1.0);
insert into grade_points values ('D-', 0.7);
insert into grade_points values ('F', 0.0);
insert into grade_points values ('NP', 0.0);
insert into grade_points values ('U', 0.0);
Expected Query 1:
Srinivasan 3
Brandt 2
Crick 2
Katz 2
My result of Query 2:
Fall 2009 9
Spring 2009 3
Summer 2009 1
Expected Query 2:
Spring 2010 7
Spring 2009 3
Fall 2009 3
Expected Query 3:
12345 Shankar 4
45678 Levy 3
1 个答案:
答案 0 :(得分：0)
因为您还在学习，所以我无法为您提供完整的解决方案。但是这里有一些准则。
第一个：
Select name AS InstructorName, count(course_id) AS NumberOfCourses
from Teaches where name IN ....
老师没有名字，您需要WHERE而不是JOIN到讲师桌
第二个：
您不需要过滤器WHERE year='2009'，他们会问您是GROUP BY year, semester，如果您GROUP BY semester，那么所有Spring学期都将在同一小组中
第三名：与第一名相同。您需要JOIN至STUDENTS
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