PLSQL开发课案例集.doc

第八章 PL/Sql开发 案例8-1 掌握INSTEAD OF类型触发器的作用和使用方法 目标 了解INSTEAD OF类型触发器的作用，掌握如何使用INSTEAD OF触发器。 步骤 1．创建一个练习表new_emps CREATE TABLE new_emps AS SELECT employee_id, last_name, salary, department_id, email, job_id, hire_date FROM employees; 2．创建一个练习表new_depts CREATE TABLE new_depts AS SELECT d.department_id, d.department_name, d.location_id, sum(e.salary) tot_dept_sal FROM employees e, departments d WHERE e.department_id = d.department_id GROUP BY d.department_id, d.department_name, d.location_id; 3．创建一个视图 CREATE VIEW emp_details AS SELECT e.employee_id, e.last_name, e.salary, e.department_id, e.email, e.job_id, d.department_name, d.location_id FROM employees e, departments d WHERE e.department_id = d.department_id; 4．创建INSTEAD OF触发器 CREATE OR REPLACE TRIGGER new_emp_dept INSTEAD OF INSERT OR UPDATE OR DELETE ON emp_details FOR EACH ROW BEGIN IF INSERTING THEN INSERT INTO new_emps VALUES (:NEW.employee_id, :NEW.last_name, :NEW.salary, :NEW.department_id, :NEW.email, :New.job_id, SYSDATE); UPDATE new_depts SET tot_dept_sal = tot_dept_sal + :NEW.salary WHERE department_id = :NEW.department_id; ELSIF DELETING THEN DELETE FROM new_emps WHERE employee_id = :OLD.employee_id; UPDATE new_depts SET tot_dept_sal = tot_dept_sal - :OLD.salary WHERE department_id = :OLD.department_id; ELSIF UPDATING (salary) THEN UPDATE new_emps SET salary = :NEW.salary WHERE employee_id = :OLD.employee_id; UPDATE new_depts SET tot_dept_sal = tot_dept_sal + (:NEW.salary - :OLD.salary) WHERE department_id = :OLD.department_id; ELSIF UPDATING (department_id) THEN UPDATE new_emps SET department_id = :NEW.department_id WHERE employee_id = :OLD.employee_id; UPDATE new_depts SET tot_dept_sal = tot_dept_sal - :OLD.salary WHERE department_id = :OLD.department_id; UPDATE new_depts SET tot_dept_sal = tot_dept_sal + :NEW.salary WHERE department_id = :NEW.department_id;