problem on checking date in trriger of before insert whether it's today date

[shashank]

i make a table with a colm of date data type and also make a before insert
trriger to check whether the entered date is sysdate or not, if not then
raise a error, but when i insert a row with sysdate it raise a error with
the message no data found. my trriger is that
create or replace trigger tr2_sysdate
before insert on kavi
declare
dat exception;
begin
if :new.a <> sysdate then
raise dat;
end if;
exception
when dat then
raise_application_error(-20001,'enter date is not systemdate');
end;
/