CREATE TABLE Departments
(Dno char(4) PRIMARY KEY,
Dname char(10),
Dheadno char(7),
FOREIGN KEY (Dheadno) REFERENCES Teachers(Tno));
CREATE TABLE Students
(Sno char(9) PRIMARY KEY,
Sname char(10) NOT NULL,
Sex char(2) CHECK (Sex = '男' OR Sex = '女'),
Birthday DATE,
Enrollyear char(4),
Speciality char(20),
Dno char(3),
FOREIGN KEY (Dno) REFERENCES Departments (Dno));
CREATE TABLE Courses
(Cno char(5) PRIMARY KEY,
Cname char(20) NOT NULL,
Period smallint,
Credit smallint);
CREATE TABLE Teachers
(Tno char(7) PRIMARY KEY,
Tname char(10) NOT NULL,
Sex char(2) CHECK (Sex = '男' OR Sex = '女'),
Birthday DATE,
Title char(6),
Dno char(4),
FOREIGN KEY (Dno) REFERENCES Departments (Dno));
CREATE TABLE Teaches
(Tno char(7),
Cno char(5),
TCscore smallint,
PRIMARY KEY (Tno,Cno),
FOREIGN KEY (Tno) REFERENCES Teachers (Tno),
FOREIGN KEY (Cno) REFERENCES Courses (Cno));
can not add foreign key constraint???
(Dno char(4) PRIMARY KEY,
Dname char(10),
Dheadno char(7),
FOREIGN KEY (Dheadno) REFERENCES Teachers(Tno));
CREATE TABLE Students
(Sno char(9) PRIMARY KEY,
Sname char(10) NOT NULL,
Sex char(2) CHECK (Sex = '男' OR Sex = '女'),
Birthday DATE,
Enrollyear char(4),
Speciality char(20),
Dno char(3),
FOREIGN KEY (Dno) REFERENCES Departments (Dno));
CREATE TABLE Courses
(Cno char(5) PRIMARY KEY,
Cname char(20) NOT NULL,
Period smallint,
Credit smallint);
CREATE TABLE Teachers
(Tno char(7) PRIMARY KEY,
Tname char(10) NOT NULL,
Sex char(2) CHECK (Sex = '男' OR Sex = '女'),
Birthday DATE,
Title char(6),
Dno char(4),
FOREIGN KEY (Dno) REFERENCES Departments (Dno));
CREATE TABLE Teaches
(Tno char(7),
Cno char(5),
TCscore smallint,
PRIMARY KEY (Tno,Cno),
FOREIGN KEY (Tno) REFERENCES Teachers (Tno),
FOREIGN KEY (Cno) REFERENCES Courses (Cno));
can not add foreign key constraint???
(Dno char(4) PRIMARY KEY,
Dname char(10),
Dheadno char(7),
); CREATE TABLE Students
(Sno char(9) PRIMARY KEY,
Sname char(10) NOT NULL,
Sex char(2) CHECK (Sex = '男' OR Sex = '女'),
Birthday date,
Enrollyear char(4),
Speciality char(20),
Dno char(4),
FOREIGN KEY (Dno) REFERENCES Departments (Dno));CREATE TABLE Courses
(Cno char(5) PRIMARY KEY,
Cname char(20) NOT NULL,
Period smallint,
Credit smallint);CREATE TABLE Teachers
(Tno char(7) PRIMARY KEY,
Tname char(10) NOT NULL,
Sex char(2) CHECK (Sex = '男' OR Sex = '女'),
Birthday date,
Title char(6),
Dno char(4),
FOREIGN KEY (Dno) REFERENCES Departments (Dno));CREATE TABLE Teaches
(Tno char(7),
Cno char(5),
TCscore smallint,
PRIMARY KEY (Tno,Cno),
FOREIGN KEY (Tno) REFERENCES Teachers (Tno),
FOREIGN KEY (Cno) REFERENCES Courses (Cno));alter table Departments
add constraint fk_dno
FOREIGN KEY(Dheadno) REFERENCES Teachers(Tno)