CREATE OR REPLACE TYPE Student_type AS OBJECT(
SSN varchar(30),
name varchar(30),
DOB DATE,
Gender CHAR(1),
age integer,
address Address_type,
)NOT FINAL;
/
CREATE OR REPLACE TYPE Master_type UNDER Student_type(
)NOT FINAL;
/CREATE OR REPLACE TYPE PHD_type UNDER Student_type(
Advisor varchar(30),
Program varchar(10)
);
/CREATE TABLE students of Student_type(
Primary key(SSN)
);CREATE TABLE MasterAssigned(
stuId varchar(30),
taskId varchar(20),
schedule TimeSchedule,
Primary key(stuID,taskId,schedule),
Foreign key(stuId) references Students(SSN)
Students IS OF (ONLY Master_type),
Foreign key(taskId) references Tasks(TaskID) TREAT Tasks.Object_Value AS PictureTask
);MasterAssigned 里stuId 如果只指master type的话, 这个foreign key 语句该怎么写呢?
谢谢大家了
SSN varchar(30),
name varchar(30),
DOB DATE,
Gender CHAR(1),
age integer,
address Address_type,
)NOT FINAL;
/
CREATE OR REPLACE TYPE Master_type UNDER Student_type(
)NOT FINAL;
/CREATE OR REPLACE TYPE PHD_type UNDER Student_type(
Advisor varchar(30),
Program varchar(10)
);
/CREATE TABLE students of Student_type(
Primary key(SSN)
);CREATE TABLE MasterAssigned(
stuId varchar(30),
taskId varchar(20),
schedule TimeSchedule,
Primary key(stuID,taskId,schedule),
Foreign key(stuId) references Students(SSN)
Students IS OF (ONLY Master_type),
Foreign key(taskId) references Tasks(TaskID) TREAT Tasks.Object_Value AS PictureTask
);MasterAssigned 里stuId 如果只指master type的话, 这个foreign key 语句该怎么写呢?
谢谢大家了
stuId varchar(30),
taskId varchar(20),
schedule TimeSchedule,
Primary key(stuID,taskId,schedule),
constraint fk_name foreign key (stuId) references Students (SSN),
......
stuId varchar(30),
taskId varchar(20),
schedule TimeSchedule,
Primary key(stuID,taskId,schedule),
foreign key (stuId) references Students (SSN),
......