Kathy Lo wrote:
On 11/21/07, Richard Huxton <dev@xxxxxxxxxxxx> wrote:
You probably shouldn't attach any meaning to the numbers from a sequence - they're just guaranteed to be unique, nothing else.
What you say here contradicts the following.
Actually, the sequence is formed by 4-digit of year and 6-digit of sequence.
So you *are* attaching significance to the number (by adding the current year to the front of it).
> So, it is required to change and restart the range of
sequence at the beginning of every year. For example, at the beginning of 2008, the sequence should be changed to the range of 2008000001 - 2008999999 and restart at 2008000001. In the time of changing the sequence, it does not allow any users to get the unique number from this sequence. However, our staff don't want to do it manually because it is difficult for them to make sure no one accessing the sequence and our service cannot stop at that time. Therefore, I need to let the users to wait in the period of changing the sequence.
Don't block users - have multiple sequences. If you define my_seq_2007, my_seq_2008, my_seq_2009 etc and then wrap access to them in a function you can EXTRACT() the year from the CURRENT_DATE and use that to form your per-year unique value.
-- Richard Huxton Archonet Ltd ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
