• Find the ID, names of all the students from departments whose name contain character ‘功’.

mysql> select id, name, dept_name from student where dept_name like '%功%'; +-------+--------+-----------+ | id | name | dept_name | +-------+--------+-----------+ | 00128 | 丘處機(jī) | 內(nèi)功學(xué)院 | | 12345 | 段譽(yù) | 內(nèi)功學(xué)院 | | 54321 | 楊過 | 內(nèi)功學(xué)院 | | 76543 | 段正淳 | 內(nèi)功學(xué)院 | +-------+--------+-----------+ 4 rows in set

• Find the ID, names and total credits of students in 邪門學(xué)院 department or in 兵器學(xué)院 department whose total credits are higher than 50 credits.

//AND和OR的優(yōu)先級(jí):AND > OR, 去掉括號(hào)結(jié)果錯(cuò)誤!!! mysql> select id, name, tot_cred,dept_name-> from student-> where (dept_name='邪門學(xué)院' or dept_name='兵器學(xué)院') and tot_cred>50; +-------+--------+----------+-----------+ | id | name | tot_cred | dept_name | +-------+--------+----------+-----------+ | 19991 | 林平之 | 80 | 兵器學(xué)院 | | 23121 | 穆念慈 | 110 | 兵器學(xué)院 | | 44553 | 藍(lán)鳳凰 | 56 | 邪門學(xué)院 | | 76653 | 胡斐 | 60 | 兵器學(xué)院 | | 98765 | 李莫愁 | 98 | 兵器學(xué)院 | +-------+--------+----------+-----------+ 5 rows in set

• For the instructor 83821, show course_id and title of all courses taught by the instructor.

mysql> select course.course_id, title, sec_id-> from course, teaches-> where course.course_id = teaches.course_id and id='83821'; +-----------+----------+--------+ | course_id | title | sec_id | +-----------+----------+--------+ | cn2 | 九陰真經(jīng) | 1 | | cn2 | 九陰真經(jīng) | 2 | | cn4 | 易筋經(jīng) | 2 | +-----------+----------+--------+ 3 rows in set

• As above, but show the total number of credits for such courses (taught by that instructor). You should use SQL aggregation on courses taught by that instructor.

mysql> select course.course_id, title, sum(credits)-> from course, teaches-> where course.course_id=teaches.course_id and id='83821'-> group by course.course_id, title; +-----------+----------+--------------+ | course_id | title | sum(credits) | +-----------+----------+--------------+ | cn2 | 九陰真經(jīng) | 8 | | cn4 | 易筋經(jīng) | 3 | +-----------+----------+--------------+ 2 rows in set

• As above, but display the total credits for each of the instructors, along with the ID of the instructor; don’t bother about the name of the instructors. (Don’t bother about instructors who have not taught any course, they can be omitted)

mysql> select id, sum(credits)-> from teaches, course-> where course.course_id=teaches.course_id-> group by id; +-------+--------------+ | id | sum(credits) | +-------+--------------+ | 10101 | 10 | | 12121 | 3 | | 15151 | 3 | | 22222 | 4 | | 32343 | 3 | | 45565 | 7 | | 76766 | 8 | | 83821 | 11 | | 98345 | 3 | +-------+--------------+ 9 rows in set

• Find average instructors’ salaries for each of courses, along with the course_id and title of the course, taught by instructors of 內(nèi)功學(xué)院, the result should be sorted from the lowest to the highest according to the average salaries.

mysql> select course.course_id, title, avg(salary)-> from course, instructor, teaches-> where instructor.id=teaches.id and teaches.course_id=course.course_id and instructor.dept_name='內(nèi)功學(xué)院'-> group by course.course_id, title-> order by avg(salary); +-----------+----------+-------------+ | course_id | title | avg(salary) | +-----------+----------+-------------+ | cn5 | 太極 | 65000 | | cn3 | 九陽神功 | 65000 | | cn1 | 內(nèi)功基礎(chǔ) | 70000 | | cn4 | 易筋經(jīng) | 83500 | | cn2 | 九陰真經(jīng) | 92000 | +-----------+----------+-------------+ 5 rows in set

• Find the names of all courses which have been taught in 南疆雨林 ever. (there should be no duplicate names)

mysql> select distinct title-> from course, section-> where course.course_id=section.course_id and building='南疆雨林'; +----------+ | title | +----------+ | 槍法 | | 內(nèi)功基礎(chǔ) | | 坑蒙拐騙 | +----------+ 3 rows in set

• Display the IDs and names of all students who have never registered for a course.

mysql> select id, name-> from student-> where tot_cred=0; +-------+------+ | id | name | +-------+------+ | 70557 | 楊康 | +-------+------+ 1 row in set

• Find the id and names of the courses which have been registered by some students without evaluated grade.

mysql> select course.course_id, title, grade-> from course, takes-> where course.course_id=takes.course_id and grade is null; +-----------+-------+-------+ | course_id | title | grade | +-----------+-------+-------+ | cq2 | 散打 | NULL | +-----------+-------+-------+ 1 row in set

• Find the courses which are the Subsequence courses of other courses. The result should involve the ids and titles of the Subsequence courses and the ids and titles of its prerequisites. (note: the names of columns in result should show the roles of the courses clearly)

mysql> select a.course_id, a.title SUB, b.course_id, b.title PRE-> from course a, course b, prereq-> where a.course_id=prereq.course_id and b.course_id=prereq.prereq_id; +-----------+----------+-----------+----------+ | course_id | SUB | course_id | PRE | +-----------+----------+-----------+----------+ | cn2 | 九陰真經(jīng) | cn1 | 內(nèi)功基礎(chǔ) | | cn3 | 九陽神功 | cn1 | 內(nèi)功基礎(chǔ) | | cn4 | 易筋經(jīng) | cn1 | 內(nèi)功基礎(chǔ) | | cn5 | 太極 | cn1 | 內(nèi)功基礎(chǔ) | | cq2 | 散打 | cq1 | 少林長(zhǎng)拳 | | cq3 | 自由搏擊 | cq1 | 少林長(zhǎng)拳 | +-----------+----------+-----------+----------+ 6 rows in set

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