问Oracle顶点身份验证方案登录错误

EN

select count(*) 
into l_count
from student,
     admin,
     organisation
where upper(p_username) in (upper(student.student_id),
                            upper(admin.admin_id),
                            upper(organisation.org_id)
                           )
  and upper(p_password) in (upper(student.student_password),
                            upper(admin.admin_password),
                            upper(organisation.org_password)
                           );

select ...
from student 
where ...
union all
select ...
from admin
where ...

declare
  ln_exists pls_integer;
begin
  select count(*)
  into ln_exists
  from dual
  where exists (
     select null 
     from your_table -- whatever you're looking for
     where id = p_id
  );
  return ln_exists = 1; -- true if exists
 end;

With valid_student as (
select count(*) as student_result 
from student 
where upper (p_username) = upper(student_id)
And upper(p_password) = upper(student_password)
),
valid_Admin as (
select count(*) as admin_result 
from admin
where upper (p_username) = upper(admin_id)
And upper(p_password) = upper(admin_password)
),
valid_org as (
select count(*) as org_result 
from organisation 
where upper (p_username) = upper(org_id)
And upper(p_password) = upper(org_password)
)
Select “Valid” as access_allowed
From valid_student s, valid_admin a, valid_org o
 Where s.student_result = 1 or a.admin_result = 1 or o.org_result = 1