PRAGMA EXCEPTION_INIT

开始

set serveroutput on;



DEFINE p_deptno = 10



DECLARE

   e_emps_remaining EXCEPTION;

   

   PRAGMA EXCEPTION_INIT

    (e_emps_remaining, -2292);



BEGIN

   DELETE FROM dept  WHERE deptno = & p_deptno;

   

   COMMIT;



EXCEPTION

   WHEN  e_emps_remaining THEN

      DBMS_OUTPUT.PUT_LINE('Cannot remove dept' || TO_CHAR(&p_deptno) || '. Employees exist. ');



END;

运行结果：

anonymous block completed

Cannot remove dept10. Employees exist. 

至于为何，那是因为在 emp 表上有 constraint 存在。

     CONSTRAINT "FK_DEPTNO" FOREIGN KEY ("DEPTNO")

      REFERENCES "SCOTT"."DEPT" ("DEPTNO") ENABLE

 

结束