帮我看看TRIGGER哪里写错了？

[零基础学编程by学哥]

CREATE OR REPLACE TRIGGER trg_dropdeny
before drop on database
begin
v_username varchar2(100);

select username into v_username from user_users;

if (lower(ora_dict_obj_name())='t1') and (v_username='tetra0')
then
raise_application_error(
num=>-20000,
msg=>'You can not delete table ' || ora_dict_obj_name() || ' ! ');
end if;
end;
/

[space6212327]

报什么错啊？

[fengwei004]

CREATE OR REPLACE TRIGGER trg_dropdeny
before drop on database
DECLARE
CURSOR p_username is
selecet username from user_users;

v_username user_users.username%type;

begin

open p_username;
fetch p_username into v_username;
close p_username;
if(lower(ora_dict_obj_name())='tl') and (v_username='tetra0')
then
raise_application_error(
num=>-20000,
msg=>'You can not delete table ' || ora_dict_obj_name() || ' ! ');
end if;
end;