temp.txt

orale培训教材包括了所有的sql说明和实例

--对constraint_trigger.txt加上after insert 
--create trigger:修改constranit表（dept_new）的primary key.
CREATE OR REPLACE TRIGGER cascade_updates
after insert or  UPDATE  on emp
  FOR EACH ROW
   BEGIN
   	
 	UPDATE dept_new
 	SET    dept_new.deptno = :new.deptno
	WHERE  dept_new.deptno = :old.deptno;
   END;


   insert into emp(empno,ename) values(78,'78'); 



   ------------------------old constraint------------------
   --change data in a constraint table
--create constraint
ALTER TABLE dept ADD CONSTRAINT fk_emp FOREIGN KEY(deptno) REFERENCES emp(deptno);

--create trigger
CREATE OR REPLACE TRIGGER cascade_updates
  AFTER UPDATE OF  on DEPT
  FOR EACH ROW
   BEGIN
	--在trigger中以dept表的更改值更改emp（约束表）
 	UPDATE emp
 	SET    emp.deptno = :new.deptno
	WHERE  emp.deptno = :old.deptno;
   END;
--update test,更改dept表
UPDATE dept SET    deptno = 1
WHERE  deptno = 30;

insert into 



CREATE OR REPLACE TRIGGER cascade_updates
  AFTER UPDATE  on dept_new
  FOR EACH ROW
   BEGIN
   	
 	UPDATE emp
 	SET    emp.deptno = :new.deptno
	WHERE  emp.deptno = :old.deptno;
   END;