@SovietPower 2022-05-06T08:58:11.000000Z 字数 18166 阅读 1214

数据库系统实验3 存储过程和触发器

DB

数据库系统实验3 存储过程和触发器
- 函数
- 过程
- 触发器
- 递归
- 高级聚集函数

https://opengauss.org/zh/docs/3.0.0/docs/Developerguide/%E5%9F%BA%E6%9C%AC%E7%BB%93%E6%9E%84.html

创建函数格式如下。[lang]根据语法可选plpgsql或sql。
注意最后还需要一个;结束语句。
如果函数体只需一条语句，则使用sql可删掉declare begin end。

create or replace function public.func (arg varchar(20))
returns integer as $$
    declare
    begin
    end;
    $$ LANGUAGE [lang];

创建过程。
注意最后还需要一个换行/结束语句。

create or replace procedure public.proc (x in varchar(20), y out integer) as
    begin
        select count(*) into d_count from instructor
        where instructor.dept_name = d_name;
    end;
/

函数

运行创建的容器。

PS H:\> docker start opengauss
PS H:\> docker exec -it opengauss bash
root@97375c3acbd1:/# su omm
omm@97375c3acbd1:/$ gsql -d db2022 -r
gsql ((openGauss 2.1.0 build 590b0f8e) compiled at 2021-09-30 14:29:04 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
db2022=#

4. 创建dept_count
统计指定院系的教师数量。

db2022=# create or replace function public.dept_count (d_name varchar(20))
db2022-# returns integer
db2022-# LANGUAGE plpgsql
db2022-# as $$
db2022$#     declare
db2022$#         res integer;
db2022$#     begin
db2022$#         select count(*) into res from instructor where dept_name=d_name;
db2022$#         return res;
db2022$#     end; $$;
CREATE FUNCTION

5. 执行dept_count

db2022=# select dept_name, budget
db2022-# from department
db2022-# where dept_count(dept_name)>4;
 dept_name  |  budget
------------+-----------
 Athletics  | 734550.70
 Statistics | 395051.74
(2 rows)

6. 创建instructor_of
返回指定院系中的所有教师的信息。返回一张表。

db2022=# create or replace function public.instructor_of (d_name varchar(20))
db2022-# returns table(
db2022(#     ID varchar(5),
db2022(#     name varchar(20),
db2022(#     dept_name varchar(20),
db2022(#     salary numeric(8,2)
db2022(# )
db2022-# LANGUAGE sql as $$
db2022$#     select ID, name, dept_name, salary from instructor
db2022$#     where instructor.dept_name=d_name;
db2022$#     $$;
CREATE FUNCTION

7. 调用instructor_of

db2022=# select * from instructor_of('Finance');
  id  |  name  | dept_name |  salary
------+--------+-----------+-----------
 6569 | Mingoz | Finance   | 115311.38
(1 row)

过程

8. 创建dept_count_proc

db2022=# create procedure public.dept_count_proc (d_name in varchar(20), d_count out integer) as
db2022$#     begin
db2022$#         select count(*) into d_count from instructor
db2022$#         where instructor.dept_name = d_name;
db2022$#     end;
db2022$# /
CREATE PROCEDURE

9. 调用dept_count_proc

db2022=# call dept_count_proc('Physics', d_count);
 d_count
---------
       2
(1 row)

10. 创建register_student
为学生注册课程。

create or replace procedure public.register_student (
    s_id in varchar(5), s_course_id in varchar(8),
    s_sec_id in varchar(8), s_semester in varchar(6),
    s_year in numeric(4,0), msg out varchar(100)
) as
    declare
        enrollment integer;
        lim integer;
    begin
        select count(*) into enrollment from takes
            where course_id = s_course_id and sec_id = s_sec_id and semester=s_semester and year=s_year;
        select capacity into lim from classroom natural join section
            where course_id = s_course_id and sec_id = s_sec_id and semester=s_semester and year=s_year;
        if (enrollment < lim) then
            begin
                insert into takes values(s_id, s_course_id, s_semester, s_year, null);
                msg := 'Successful!';
            end;
        else
            msg := 'Enrollment limit reached for course' || s_course_id || ' section' || s_sec_id;
        end if;
    end;
/

db2022=# create or replace procedure public.register_student (
db2022(#     s_id in varchar(5), s_course_id in varchar(8),
db2022(#     s_sec_id in varchar(8), s_semester in varchar(6),
db2022(#     s_year in numeric(4,0), msg out varchar(100)
db2022(# ) as
db2022$#     declare
db2022$#         enrollment integer;
db2022$#         lim integer;
db2022$#     begin
db2022$#         select count(*) into enrollment from takes
db2022$#             where course_id = s_course_id and sec_id = s_sec_id and semester=s_semester and year=s_year;
db2022$#         select capacity into lim from classroom natural join section
db2022$#             where course_id = s_course_id and sec_id = s_sec_id and semester=s_semester and year=s_year;
db2022$#         if (enrollment < lim) then
db2022$#             begin
db2022$#                 insert into takes values(s_id, s_course_id, s_semester, s_year, null);
db2022$#                 msg := 'Successful!';
db2022$#             end;
db2022$#         else
db2022$#             msg := 'Enrollment limit reached for course' || s_course_id || ' section' || s_sec_id;
db2022$#         end if;
db2022$#     end;
db2022$# /
CREATE PROCEDURE

11. 调用register_student

db2022=# call register_student('1018','169','1','Spring','2007',msg);
                      msg
------------------------------------------------
 Enrollment limit reached for course169 section1
(1 row)
db2022=# call register_student('1018','258','1','Fall','2007',msg);
                      msg
------------------------------------------------
 Enrollment limit reached for course258 section1
(1 row)

12. 创建test_proc
为该课程在新学期开设一个新的section。该课程所属院系的学生如果之前没有修过该课程，则为其注册该课程。

create or replace procedure public.test_proc (cid in varchar(8), sec in varchar(8), sem varchar(6), y numeric(4,0)) as
    declare
        dept varchar(20);
        cred numeric(2,0);
    begin
        create temporary table stu(id varchar(5));
        insert into section values(cid, sec, sem, y, null, null, null);
        select dept_name into dept from course where course_id=cid;
        select credits into cred from course where course_id=cid;
        insert into stu
            (select ID from student where dept_name=dept)
            except
            (select ID from student natural join takes
            where dept_name=dept and course_id=cid);
        insert into takes
            select ID, cid, sec, sem, y, null
            from stu;
        update student
        set tot_cred = tot_cred+cred
        where student.ID in (select ID from stu);
    end;
/

db2022=# create or replace procedure public.test_proc (cid in varchar(8), sec in varchar(8), sem varchar(6), y numeric(4,0)) as
db2022$#     declare
db2022$#         dept varchar(20);
db2022$#         cred numeric(2,0);
db2022$#     begin
db2022$#         create temporary table stu(id varchar(5));
db2022$#         insert into section values(cid, sec, sem, y, null, null, null);
db2022$#         select dept_name into dept from course where course_id=cid;
db2022$#         select credits into cred from course where course_id=cid;
db2022$#         insert into stu
db2022$#             (select ID from student where dept_name=dept)
db2022$#             except
db2022$#             (select ID from student natural join takes
db2022$#             where dept_name=dept and course_id=cid);
db2022$#         insert into takes
db2022$#             select ID, cid, sec, sem, y, null
db2022$#             from stu;
db2022$#         update student
db2022$#         set tot_cred = tot_cred+cred
db2022$#         where student.ID in (select ID from stu);
db2022$#     end;
db2022$# /
CREATE PROCEDURE
db2022=# select * from takes where id='52157';
  id   | course_id | sec_id | semester | year | grade
-------+-----------+--------+----------+------+-------
...
 52157 | 747       | 1      | Spring   | 2004 | A+
 52157 | 338       | 1      | Spring   | 2007 | A-
(18 rows)
db2022=# select * from student where id='52157';
  id   | name  | dept_name | tot_cred
-------+-------+-----------+----------
 52157 | Nagle | Astronomy |       62
(1 row)
db2022=# call test_proc('489', '1', 'Spring', 2022);
 test_proc
-----------
(1 row)
db2022=# select * from takes where id='52157';
  id   | course_id | sec_id | semester | year | grade
-------+-----------+--------+----------+------+-------
...
 52157 | 747       | 1      | Spring   | 2004 | A+
 52157 | 338       | 1      | Spring   | 2007 | A-
 52157 | 489       | 1      | Spring   | 2022 |
(19 rows)
db2022=# select * from student where id='52157';
  id   | name  | dept_name | tot_cred
-------+-------+-----------+----------
 52157 | Nagle | Astronomy |       66
(1 row)

触发器

与其它数据库管理系统不同，openGauss在创建触发器时并不直接包含所执行的处理逻辑，而是将处理逻辑放在事先创建的不
带参数且返回类型为TRIGGER的函数中，在触发器的定义中指定调用该函数。
openGauss不支持函数中使用COMMIT/ROLLBACK/SAVEPOINT（包括函数调用含有COMMIT/ROLLBACK/SAVEPOINT的存储过程）。
openGauss不支持TRIGGER中调用含有COMMIT/ROLLBACK/SAVEPOINT语句的存储过程。

13. 为触发器创建函数 tri_insert_section_func 和 tri_delete_timeslot_func

create or replace function public.tri_insert_section_func ()
returns trigger
not fenced not shippable as $$
    declare
    begin
        if new.time_slot_id not in (select time_slot_id from time_slot) then
            delete from section
            where course_id=new.course_id and sec_id=new.sec_id and semester=new.semester and year=new.year;
            raise exception 'time_slot table中不存在指定的time_slot_it，insert失败.';
        end if;
        return new;
    end;
    $$ LANGUAGE plpgsql;
create or replace function public.tri_delete_timeslot_func ()
returns trigger
not fenced not shippable as $$
    declare
    begin
        if old.time_slot_id not in (select time_slot_id from time_slot) and old.time_slot_id in (select time_slot_id from section) then
            insert into time_slot values(old.time_slot_id, old.day, old.start_hr, old.start_min, old.end_hr, old.end_min);
            raise exception 'time_slot_id仍被section引用，delete失败.';
        end if;
        return old;
    end;
    $$ LANGUAGE plpgsql;

db2022=# create or replace function public.tri_insert_section_func ()
db2022-# returns trigger
db2022-# not fenced not shippable as $$
db2022$#     declare
db2022$#
db2022$#     begin
db2022$#         if new.time_slot_id not in (select time_slot_id from time_slot) then
db2022$#             delete from section
db2022$#             where course_id=new.course_id and sec_id=new.sec_id and semester=new.semester and year=new.year;
db2022$#             raise exception 'time_slot table中不存在指定的time_slot_it，insert失败.';
db2022$#         end if;
db2022$#         return new;
db2022$#     end;
db2022$#     $$ LANGUAGE plpgsql;
CREATE FUNCTION
db2022=# create or replace function public.tri_delete_timeslot_func ()
db2022-# returns trigger
db2022-# not fenced not shippable as $$
db2022$#     declare
db2022$#
db2022$#     begin
db2022$#         if old.time_slot_id not in (select time_slot_id from time_slot) and old.time_slot_id in (select time_slot_id from section) then
db2022$#             insert into time_slot values(old.time_slot_id, old.day, old.start_hr, old.start_min, old.end_hr, old.end_min);
db2022$#             raise exception 'time_slot_id仍被section引用，delete失败.';
db2022$#         end if;
db2022$#         return old;
db2022$#     end;
db2022$#     $$ LANGUAGE plpgsql;
CREATE FUNCTION

14. 创建触发器 insert_section_timeslot_check 和 delete_timeslot_check

db2022=# create trigger insert_section_timeslot_check after insert on section
db2022-#     for each row
db2022-#     execute procedure tri_insert_section_func();
CREATE TRIGGER
db2022=# create trigger delete_timeslot_check after delete on time_slot
db2022-#     for each row
db2022-#     execute procedure tri_delete_timeslot_func();
CREATE TRIGGER

15. 检查触发器 insert_section_timeslot_check 效果

db2022=# select * from time_slot where time_slot_id = 'Q';
 time_slot_id | day | start_hr | start_min | end_hr | end_min
--------------+-----+----------+-----------+--------+---------
(0 rows)
db2022=# insert into section values('747','1','Fall',2021,'Gates','314','Q');
ERROR:  time_slot table中不存在指定的time_slot_it，insert失败.
db2022=# select * from section where course_id = '747' and sec_id = '1' and semester = 'Fall' and year = 2021;
 course_id | sec_id | semester | year | building | room_number | time_slot_id
-----------+--------+----------+------+----------+-------------+--------------
(0 rows)
db2022=# insert into time_slot values('Q','W',10,0,12,30);
INSERT 0 1
db2022=# insert into section values('747','1','Fall',2021,'Gates','314','Q');
INSERT 0 1
db2022=# select * from section where course_id = '747' and sec_id = '1' and semester = 'Fall' and year = 2021;
 course_id | sec_id | semester | year | building | room_number | time_slot_id
-----------+--------+----------+------+----------+-------------+--------------
 747       | 1      | Fall     | 2021 | Gates    | 314         | Q
(1 row)

16. 检查触发器 delete_timeslot_check 效果

db2022=# insert into time_slot values('Q','F',10,0,12,30);
INSERT 0 1
db2022=# select * from time_slot where time_slot_id = 'Q';
 time_slot_id | day | start_hr | start_min | end_hr | end_min
--------------+-----+----------+-----------+--------+---------
 Q            | W   |       10 |         0 |     12 |      30
 Q            | F   |       10 |         0 |     12 |      30
(2 rows)
db2022=# delete from time_slot where time_slot_id = 'Q' and day = 'W';
DELETE 1
db2022=# select * from time_slot where time_slot_id = 'Q';
 time_slot_id | day | start_hr | start_min | end_hr | end_min
--------------+-----+----------+-----------+--------+---------
 Q            | F   |       10 |         0 |     12 |      30
(1 row)
db2022=# delete from time_slot where time_slot_id = 'Q' and day = 'F';
ERROR:  time_slot_id仍被section引用，delete失败.
db2022=# select * from time_slot where time_slot_id = 'Q';
 time_slot_id | day | start_hr | start_min | end_hr | end_min
--------------+-----+----------+-----------+--------+---------
 Q            | F   |       10 |         0 |     12 |      30
(1 row)
db2022=# select * from section where time_slot_id = 'Q';
 course_id | sec_id | semester | year | building | room_number | time_slot_id
-----------+--------+----------+------+----------+-------------+--------------
 747       | 1      | Fall     | 2021 | Gates    | 314         | Q
(1 row)
db2022=# delete from section where time_slot_id = 'Q';
DELETE 1
db2022=# delete from time_slot where time_slot_id = 'Q' and day = 'F';
DELETE 1
db2022=# select * from time_slot where time_slot_id = 'Q';
 time_slot_id | day | start_hr | start_min | end_hr | end_min
--------------+-----+----------+-----------+--------+---------
(0 rows)

17. 删除创建的触发器和函数

db2022=# DROP TRIGGER delete_timeslot_check on time_slot;
DROP TRIGGER
db2022=# DROP TRIGGER insert_section_timeslot_check on section;
DROP TRIGGER
db2022=# DROP FUNCTION IF EXISTS tri_insert_section_func;
DROP FUNCTION
db2022=# DROP FUNCTION IF EXISTS tri_delete_timeslot_func;
DROP FUNCTION

18. 创建触发器 tri_update_credits
用于维护学生所获得的学分。

create or replace function public.on_update_credits_func ()
returns trigger
not fenced not shippable as $$
    begin
        if new.grade<>'F' and new.grade is not null and (old.grade='F' or old.grade is null) then
            update student
            set tot_cred = tot_cred+
                (select credits from course where course.course_id=new.course_id);
        end if;
        return new;
    end;
    $$ LANGUAGE plpgsql;
create trigger on_update_credits after update on takes
    for each row
    execute procedure on_update_credits_func();

db2022=# create or replace function public.on_update_credits_func ()
db2022-# returns trigger
db2022-# not fenced not shippable as $$
db2022$#     begin
db2022$#         if new.grade<>'F' and new.grade is not null and (old.grade='F' or old.grade is null) then
db2022$#             update student
db2022$#             set tot_cred = tot_cred+
db2022$#                 (select credits from course where course.course_id=new.course_id);
db2022$#         end if;
db2022$#         return new;
db2022$#     end;
db2022$#     $$ LANGUAGE plpgsql;
CREATE FUNCTION
db2022=# create trigger on_update_credits after update on takes
db2022-#     for each row
db2022-#     execute procedure on_update_credits_func();
CREATE TRIGGER
db2022=# select * from takes where grade='F';
  id   | course_id | sec_id | semester | year | grade
-------+-----------+--------+----------+------+-------
 79446 | 808       | 1      | Fall     | 2003 | F
 99710 | 169       | 2      | Fall     | 2002 | F
 ...
db2022=# select * from student where id='99710';
  id   |    name    | dept_name | tot_cred
-------+------------+-----------+----------
 99710 | Savolainen | Languages |       50
(1 row)
db2022=#  update takes set grade='A' where id='99710' and course_id='169' and sec_id='2';
UPDATE 1
db2022=# select * from student where id='99710';
  id   |    name    | dept_name | tot_cred
-------+------------+-----------+----------
 99710 | Savolainen | Languages |       53
(1 row)

递归

19. 创建视图 rec_prereq
找出所有课程的直接和间接前导课程。

db2022=# create view rec_prereq as
db2022-#     with recursive rec_prereq(course_id, prereq_id) as (
db2022(#         select course_id, prereq_id
db2022(#         from prereq
db2022(#         union
db2022(#         select rec_prereq.course_id, prereq.prereq_id
db2022(#         from rec_prereq, prereq
db2022(#         where rec_prereq.prereq_id = prereq.course_id
db2022(#     )
db2022-#     select * from rec_prereq;
CREATE VIEW
db2022=# select * from rec_prereq where course_id='760';
 course_id | prereq_id
-----------+-----------
 760       | 169
 760       | 603
 760       | 735
(3 rows)

高级聚集函数

20. 创建视图 students_gpa
显示学生的GPA。

db2022=# create view students_gpa as
db2022-#     select id, name, round(sum(point*credits)/sum(credits), 1) as GPA
db2022-#     from student natural left outer join (
db2022(#         select id, takes.course_id, course.credits, max(point) as point
db2022(#         from takes, grade_point, course
db2022(#         where trim(takes.grade) = grade_point.grade and takes.course_id = course.course_id
db2022(#         group by id, takes.course_id, course.credits
db2022(#     ) group by id, name;
CREATE VIEW
db2022=# select * from students_gpa where name='Cox';
  id   | name | gpa
-------+------+-----
 59908 | Cox  | 2.8
 21766 | Cox  | 3.0
 44304 | Cox  | 3.4
(3 rows)

21. 查询学生的GPA排名

db2022=# select ID, name, gpa, rank() over (order by (GPA) desc) as s_rank
db2022-# from students_gpa
db2022-# limit 5;
  id   |  name   | gpa | s_rank
-------+---------+-----+--------
 79446 | Frost   |     |      1
 56499 | Zarpell | 3.9 |      2
 81896 | Feldman | 3.9 |      2
 18286 | Pang    | 3.9 |      2
 98619 | Nagaraj | 3.9 |      2
(5 rows)
db2022=# select ID, name, rank() over (order by GPA desc nulls last) as s_rank
db2022-# from students_gpa
db2022-# limit 5;
  id   |  name   | s_rank
-------+---------+--------
 98619 | Nagaraj |      1
 18286 | Pang    |      1
 56499 | Zarpell |      1
 81896 | Feldman |      1
 4248  | Wright  |      5
(5 rows)
db2022=# select ID, (1 + (select count(*) from students_gpa B where B.GPA > A.GPA)) as s_rank
db2022-# from students_gpa A
db2022-# order by s_rank
db2022-# limit 5;
  id   | s_rank
-------+--------
 81896 |      1
 79446 |      1
 18286 |      1
 98619 |      1
 56499 |      1
(5 rows)

22. 创建视图 dept_grades
显示学生的GPA，包含其院系。

db2022=# create view dept_grades as
db2022-#     select id, name, dept_name, round(sum(point*credits)/sum(credits), 1) as GPA
db2022-#     from student natural left outer join (
db2022(#         select id, takes.course_id, course.credits, max(point) as point
db2022(#         from takes, grade_point, course
db2022(#         where trim(takes.grade) = grade_point.grade and takes.course_id = course.course_id
db2022(#         group by id, takes.course_id, course.credits
db2022(#     ) group by id, name;
CREATE VIEW
db2022=# select * from dept_grades;
  id   |        name        |  dept_name  | gpa
-------+--------------------+-------------+-----
 92776 | Oki                | Psychology  | 2.4
 94894 | Kozlov             | Accounting  | 2.7
 26881 | Markin             | History     | 3.0
...

23. 按院系查询学生的GPA排名

db2022=# select ID, dept_name, gpa,
db2022-#     rank () over (partition by dept_name order by GPA desc) as dept_rank
db2022-# from dept_grades
db2022-# order by dept_name, dept_rank
db2022-# limit 3;
  id   | dept_name  | gpa | dept_rank
-------+------------+-----+-----------
 69679 | Accounting | 3.8 |         1
 14829 | Accounting | 3.5 |         2
 23457 | Accounting | 3.5 |         2
(3 rows)

24. 创建视图 tot_credits
统计所有学生每年所获得的总学分。

db2022=# create view tot_credits(year,credits) as
db2022-#     with temp1(year, credits) as
db2022-#         (select year, sum(credits) from takes natural join course
db2022(#         where grade <> 'F' or grade is not null
db2022(#         group by year),
db2022-#     temp2(year, credits) as
db2022-#         (select 2001,0 union select 2002,0 union
db2022(#         select 2003,0 union select 2004,0 union
db2022(#         select 2005,0 union select 2006,0 union
db2022(#         select 2007,0 union select 2008,0 union
db2022(#         select 2009,0 union select 2010,0 union
db2022(#         select 2011,0 union select 2012,0 union
db2022(#         select 2013,0 union select 2014,0 union
db2022(#         select 2015,0 union select 2016,0 union
db2022(#         select 2017,0 union select 2018,0 union
db2022(#         select 2019,0 union select 2020,0 union
db2022(#         select 2021,0 union select 2022,0)
db2022-#     select * from temp1
db2022-#     UNION
db2022-#     select * from temp2 where year not in (select year from temp1);
CREATE VIEW
db2022=# select * from tot_credits limit 3;
 year | credits
------+---------
 2012 |       0
 2004 |    7085
 2018 |       0
(3 rows)

25. 使用窗口函数查询不同条件下所有学生所获得的平均学分

db2022=# select year, round(avg(credits) over (order by year rows 3 preceding), 2)
db2022-# as avg_total_credits
db2022-# from tot_credits
db2022-# limit 3;
 year | avg_total_credits
------+-------------------
 2001 |           4530.00
 2002 |           8984.00
 2003 |          10307.00
(3 rows)
db2022=# select year, round(avg(credits) over (order by year rows unbounded preceding), 2)
db2022-# as avg_total_credits
db2022-# from tot_credits
db2022-# limit 3;
 year | avg_total_credits
------+-------------------
 2001 |           4530.00
 2002 |           8984.00
 2003 |          10307.00
(3 rows)
db2022=# select year, round(avg(credits) over (order by year rows between 3 preceding and 2 following), 2)
db2022-# as avg_total_credits
db2022-# from tot_credits
db2022-# limit 3;
 year | avg_total_credits
------+-------------------
 2001 |          10307.00
 2002 |           9501.50
 2003 |           9362.20
(3 rows)

26. 创建视图 student_tot_credits(id, year, credits)
统计每个学生每年所获得的总学分。

db2022=# create view student_tot_credits as
db2022-#     select ID, year, sum(course.credits) as credits
db2022-#     from takes natural join course
db2022-#     group by ID, year;
CREATE VIEW
db2022=# select * from student_tot_credits limit 3;
  id   | year | credits
-------+------+---------
 108   | 2006 |       4
 58874 | 2007 |       4
 22618 | 2002 |       3
(3 rows)

27. 查询每个学生连续三年所获得的平均学分数

select ID, year, round(avg(credits)
                    over (partition by ID order by year rows 3 preceding), 2)
from student_tot_credits;

db2022=# select * from student_tot_credits where id='108';
 id  | year | credits
-----+------+---------
 108 | 2006 |       4
 108 | 2010 |       7
 108 | 2004 |       4
 108 | 2001 |       3
 108 | 2008 |      11
 108 | 2002 |      10
 108 | 2007 |      10
 108 | 2003 |       7
(8 rows)
db2022=# select ID, year, round(avg(credits)
db2022(#                     over (partition by ID order by year rows 3 preceding), 2)
db2022-# from student_tot_credits where id='108';
 id  | year | round
-----+------+-------
 108 | 2001 |  3.00
 108 | 2002 |  6.50
 108 | 2003 |  6.67
 108 | 2004 |  6.00
 108 | 2006 |  6.25
 108 | 2007 |  6.25
 108 | 2008 |  7.25
 108 | 2010 |  8.00
(8 rows)

数据库系统 实验3 存储过程和触发器

函数

过程

触发器

递归

高级聚集函数

内容目录

数据库系统实验3 存储过程和触发器