Oracle：在对象关系数据库中使用外键

Question

我有一个关于在 oracle 的对象关系数据库中使用主键和外键的问题。下面是我的 sql 代码和插入语句。我正在尝试创建一个包含学生、课程、教师和部门的简单数据库。但是每当我运行下面的 select 语句时，我都看不到我输入的 DepartmentID 和 TeacherID。相反，我得到 [HR.DEPARTMENT_OBJTYP] 作为部门 ID 的值，同样是教师 ID。这是因为我引用了整个部门，而不仅仅是课程表中的部门 ID？我不知道如何使用外键并在对象关系数据库中正确查询它们，并且无法找到任何有用的易于理解的信息。有人可以告诉我哪里出错了吗？

例如在 Course_objtyp 中我做... TeacherID REF Teacher_objtyp。这是正确的引用方式吗，我不确定，因为我只想引用teacherID而不是整个Teacher_objtyp？

CREATE TYPE Student_objtyp AS OBJECT (
  FName         VARCHAR2(20),
  LName         VARCHAR2(20),
  StudentID     NUMBER
  ); 
/

CREATE TABLE Student_objtab OF Student_objtyp (StudentID PRIMARY KEY)
  OBJECT IDENTIFIER IS PRIMARY KEY;

CREATE TYPE Department_objtyp AS OBJECT (
  DeptID NUMBER,
  DeptName VARCHAR2(20)
  );
/  

CREATE TABLE Department_objtab OF Department_objtyp (DeptID PRIMARY KEY)
  OBJECT IDENTIFIER IS PRIMARY KEY;

CREATE TYPE Teacher_objtyp AS OBJECT (
  TeacherID NUMBER,
  FName VARCHAR2(20),
  LName VARCHAR2(20)
  );
/

CREATE TABLE Teacher_objtab OF Teacher_objtyp (TeacherID PRIMARY KEY)
  OBJECT IDENTIFIER IS PRIMARY KEY;

CREATE TYPE Course_objtyp AS OBJECT (
  CourseName VARCHAR(20),
  CourseID NUMBER,
  DeptID REF Department_objtyp,
  TeacherID REF Teacher_objtyp
  );
/

CREATE TABLE Course_objtab OF Course_objtyp (
  PRIMARY KEY (CourseID),
  FOREIGN KEY (DeptID) REFERENCES Department_objtab,
  FOREIGN KEY (TeacherID) REFERENCES Teacher_objtab)
/

INSERT INTO Student_objtab VALUES('bill','smitts',1);
INSERT INTO Student_objtab VALUES('bob','jo',2);

INSERT INTO Teacher_objtab VALUES(1,'Mr','Higgins');

INSERT INTO Department_objtab VALUES(1111,'Science');

INSERT INTO Course_objtab
SELECT 'Chem101',001,
REF(D),
REF(T)
FROM Department_objtab D, Teacher_objtab T
WHERE D.DeptID = 1111 and T.TeacherID = 1;

我尝试运行的非常简单的选择语句：

select * from Course_objtab;

Answer 1

以下工作正常，但我不确定您是否正在寻找。

CREATE TYPE Course_objtyp AS OBJECT (
  CourseName VARCHAR(20),
  CourseID NUMBER,
  DeptID Number,
  TeacherID Number
  );

CREATE TABLE Course_objtab OF Course_objtyp (
  PRIMARY KEY (CourseID),
  FOREIGN KEY (DeptID) REFERENCES Department_objtab(DeptID),
  FOREIGN KEY (TeacherID) REFERENCES Teacher_objtab(TeacherID));

INSERT INTO Course_objtab
 SELECT 'Chem101',001, D.DeptID, T.TeacherID
 FROM Department_objtab D, Teacher_objtab T
 WHERE D.DeptID = 1111 and T.TeacherID = 1;