Exception

1.自定义异常说明
declare
  e_insert_excep exception;
  pragma exception_init(e_insert_excep,-1400);
begin
 insert into departments(department_id,department_name) values(280,null);
 exception when e_insert_excep then
   dbms_output.put_line('Insert operation failed');
   dbms_output.put_line(sqlerrm);
end;
执行结果：
Insert operation failed
ORA-01400: 无法将 NULL 插入 ("HR"."DEPARTMENTS"."DEPARTMENT_NAME")