MySQL实现关系代数运算

MySQL实现关系代数运算

MySQL实现关系代数运算

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两表的所有元组

select * from department;

select * from instructor;

笛卡尔积结果

select * from instructor, department;

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两表的所有元组

select * from department

select * from department0

并运算结果

select * from department

union

select * from department0;

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两表的所有元组

交运算

select * from department

inner join department0 on department.building = department0.building;

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两表的所有元组

差运算 NOT IN

select * from department

where building not in

(select building from department0);

差运算 LFET JOIN

select * from department

left join department0 on department.building = department0.building

where department0.building is null;

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表

选择结果

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表

投影结果

select name from instructor;

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表

自然连接结果

select * from course natural join department;

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create table department

(dept_name varchar(20),

building varchar(15),

budget numeric(12, 2),

primary key (dept_name));

create table course(

course_id varchar(7),

title varchar(50),

credits numeric(2, 0),

primary key (course_id),

foreign key(dept_name) references department(dept_name));

create table instructor(

ID varchar(5),

name varchar(20) not null,

dept_name varchar(20),

salary numeric(8,2),

primary key(ID),

foreign key(dept_name) references department(dept_name));

create table section(

course_id varchar(8),

sec_id varchar(8),

semester varchar(6),

year numeric(4,0),

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(course_id));

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(course_id, sec_id, semester, year),

foreign key(ID) references instructor(ID));

insert into department

(dept_name, building, budget)

values

('CS', 'CS Building', 10000);

insert into department

(dept_name, building, budget)

values

('SE', 'SE Building', 10000);

insert into course

(course_id, title, dept_name, credits)

values

('10001', 'DS', 'CS', 5);

insert into course

(course_id, title, dept_name, credits)

values

('10002', 'OS', 'CS', 5);

insert into course

(course_id, title, dept_name, credits)

values

('10003', 'SE', 'SE', 5);

insert into instructor

(ID, name, dept_name, salary)

values

('10001', 'Mozart', 'CS', 10000);

insert into instructor

(ID, name, dept_name, salary)

values

('10002', 'Dennis', 'CS', 20000);

insert into instructor

(ID, name, dept_name, salary)

values

('10003', 'Kim', 'SE', 15000);

insert into section

(course_id, sec_id, semester, year, building, room_number, time_slot_id)

values

('10001', '10001', '1', 2020, 'CS Building', '101', '001');

insert into section

(course_id, sec_id, semester, year, building, room_number, time_slot_id)

values

('10002', '10002', '1', 2020, 'CS Building', '103', '002');

insert into section

(course_id, sec_id, semester, year, building, room_number, time_slot_id)

values

('10003', '10003', '1', 2020, 'SE Building', '203', '003');

insert into teaches

(ID, course_id, sec_id, semester, year)

values

('10002', '10001', '10001', '1', 2020);

insert into teaches

(ID, course_id, sec_id, semester, year)

values

('10001', '10002', '10002', '1', 2020);

insert into teaches

(ID, course_id, sec_id, semester, year)

values

('10003', '10003', '10003', '1', 2020);

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数据库系统概论(第5版)

数据库系统概念(原书第6版)

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由于博主水平有限，不免有疏漏之处，欢迎读者随时批评指正，以免造成不必要的误解

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