Many to many using a primary-key and foreign-key relationship : FOREIGN KEY « Table « Oracle PL/SQL Tutorial

SQL> CREATE TABLE Course
  2     (course_id        VARCHAR2(10) NOT NULL,
  3      course_name      VARCHAR2(20),
  4      PRIMARY KEY (course_id));

Table created.

SQL>
SQL> CREATE TABLE emp
  2     (stud_id    VARCHAR2(10) NOT NULL,
  3      stud_name  VARCHAR2(20),
  4      PRIMARY KEY (stud_id));

Table created.

SQL>
SQL> CREATE TABLE Enrolls_in
  2     (course_id  VARCHAR2(10) NOT NULL,
  3      stud_id    VARCHAR2(10) NOT NULL,
  4      PRIMARY KEY (course_id, stud_id),
  5      FOREIGN KEY (course_id) REFERENCES Course (course_id)
  6      ON DELETE CASCADE,
  7      FOREIGN KEY (stud_id) REFERENCES emp (stud_id)
  8      ON DELETE CASCADE);

Table created.

SQL>
SQL> drop table Course cascade constraints;

Table dropped.

SQL> drop table emp cascade constraints;

Table dropped.

SQL> drop table Enrolls_in;

Table dropped.

SQL>

6.16.FOREIGN KEY
	6.16.1.	Adding a FOREIGN KEY Constraint
	6.16.2.	ON DELETE CASCADE clause with a FOREIGN KEY constraint
	6.16.3.	Use the ON DELETE SET NULL clause with a FOREIGN KEY constraint
	6.16.4.	ORA-02298: cannot validate (JAVA2S.PRODUCT_ORDER_FK_PRODUCT) - parent keys not found
	6.16.5.	A foreign key to reference itself
	6.16.6.	ORA-02270: no matching unique or primary key for this column-list
	6.16.7.	Add constraint foreign key references
	6.16.8.	Violate a foreign key
	6.16.9.	Disable foreign key
	6.16.10.	Many to many using a primary-key and foreign-key relationship