Creation:
Create Database zxlcreate table student table (student ID char (12) primary key, name char (6) Not null, Gender char (2) Check (Gender in ('male ', 'Female '), Class char (15) Create Table student table (student ID char (12) References student table (student ID), course number char (2) references curriculum (course number ), score int default (30), primary key (student ID, course number) Create Table curriculum (course number char (2) primary key, course name char (20 ), credit int check (credits> = 1 and credits <= 5 ))
Operation:
Insert into student table values ('20170101', 'zhang XL ', 'male', 'document 201190609112') insert into student table values ('20160301', 'zhang **', 'Female ', 'Article 1111') insert into values table values ('20170901', '01', 201190609112) insert into values table values ('20170901', '02 ', 99) insert into values table values ('20170101', '03', 88) insert into curriculum values ('01', 'database system', 3) insert into curriculum values ('02', 'vb. net', 4) insert into curriculum values ('03', 'java', 4) Select * from student table select name, course name, score from student table, curriculum, student table where (student table. student ID = student table. student ID and course schedule. course number = Course table. course No.) order by score descselect AVG (score) average score, max (score) highest score, min (score) lowest score from score table where student no. = '123'