write SQL query for: Find all students who have taken all courses taken by instr
ID: 3752105 • Letter: W
Question
write SQL query for:
Find all students who have taken all courses taken by instructor 'Srinivasan'. (This is the division operation of relational algebra.) You can implement it by counting the number of courses taught by Srinivasan, and for each student (i.e. group by student), find the number of courses taken by that student, which were taught by Srinivasan. Make sure to count each course ID only once.
//University DDL statements
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),
foreign key (dept_name) references department
on delete set null
);
create table instructor
(ID varchar(5),
name varchar(20) not null,
dept_name varchar(20),
salary numeric(8,2) check (salary > 29000),
primary key (ID),
foreign key (dept_name) references department
on delete set null
);
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),
foreign key (course_id) references course
on delete cascade,
foreign key (building, room_number) references classroom
on delete set null
);
create table teaches
(ID varchar(5),
course_id varchar(8),
sec_id varchar(8),
semester varchar(6),
year numeric(4,0),
primary key (ID, course_id, sec_id, semester, year),
foreign key (course_id,sec_id, semester, year) references section
on delete cascade,
foreign key (ID) references instructor
on delete cascade
);
create table student
(ID varchar(5),
name varchar(20) not null,
dept_name varchar(20),
tot_cred numeric(3,0) check (tot_cred >= 0),
primary key (ID),
foreign key (dept_name) references department
on delete set null
);
create table takes
(ID varchar(5),
course_id varchar(8),
sec_id varchar(8),
semester varchar(6),
year numeric(4,0),
grade varchar(2),
primary key (ID, course_id, sec_id, semester, year),
foreign key (course_id,sec_id, semester, year) references section
on delete cascade,
foreign key (ID) references student
on delete cascade
);
create table advisor
(s_ID varchar(5),
i_ID varchar(5),
primary key (s_ID),
foreign key (i_ID) references instructor (ID)
on delete set null,
foreign key (s_ID) references student (ID)
on delete cascade
);
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),
foreign key (course_id) references course
on delete cascade,
foreign key (prereq_id) references course
);
Explanation / Answer
SELECT name FROM student
WHERE ID={ SELECT ID FROM takes
WHERE course_id={ SELECT course_id FROM teaches
WHERE ID={ SELECT ID FROM instructor
WHERE name='Srinivasan'}
}
}
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