oracle自定义异常

declare
v_count number;
begin
select count(*) into v_count from dept;
if v_count < 10 then
raise_application_error(-20001,'数量小于10');
end if;
end;

declare
v_count number;
my_exp exception;
begin
select count(*) into v_count from dept;
if v_count < 10 then
raise my_exp;
end if;
exception
when my_exp then
dbms_output.put_line('数量小于10');
when others then
dbms_output.put_line('其他异常');
end;