Increment value in a field but keeping it constant throughout the day

Question

In a PRE-INSERT trigger on an application I have a problem
keeping the value in a field constant for the rest of the day
until the next day. The automatically generated number should
change only if the system date changes. How can i do this?.
The code is as below:
begin
                    update sequence_number
               set maxseqno = maxseqno + 1
                    where table_name
= 'ECONET';
begin
select maxseqno into :two.seqno from sequence_number
where table_name = 'ECONET';
end;
begin
select ltrim(to_char(:two.seqno,'00000000000000000009'))
into :two.line_number from sequence_number
where table_name = 'ECONET';
end;
begin
select ltrim(to_char(:two.seqno,'00000000000000000009'))
into :two.unique_transfer_batch from sequence_number
where table_name = 'ECONET';
end;
end;

Answer 1

The easist way is probably to store the date the sequence number
was last set, and then only increment the number if the date is
different.
If you just want a sequence number that changes once each a day,
an alternative might be to just calculate the number of days
since a particular date.
In oracle this would be something along the lines of
trunc(sysdate) - to_date('01-OCT-2001','DD-MON-YYYY') to give
the number of days since October 1st.