Re: self defined counter function

In article <1574570229(dot)20040420095643(at)radax(dot)net>,
Enrico Ortmann <pg(dot)admin(at)radax(dot)net> writes:

> Hi admins,
> I got a conceptual question on creating a stored procedure
> I need for my app. First the description of the problem:

> I need a counter which works with 36 possible values per
> character [0-9 and thereafter A-Z].
> That means if incremented it should return values as follows:
> 0000
> 0001
> 0002
> ...
> 0009
> 000A
> 000B
> 000C
> ...
> 000X
> 000Y
> 000Z
> 0010
> 0011
> 0012
> ...

> and so on.

> My question is if anybody has already implemented such a
> user-defined 'sequence' in PL/PGSql or if anyone has a great
> idea on how to do that. The only solution I see at present is
> to do that in PHP which is used to code the mentioned userland.

> I suggest to solute on doing the following.

> - I create a sequence on the DBS
> - I get the next value of this sequence
> - I convert the next value in PHP in the code I need

> The problem I see on doing this is that I always need to
> convert if I want to get any kind of information about the
> counter. For example it could be that I only want to know
> what the last given value was. Because of the high traffic
> value on the application I have to take care of, that the
> information I read is quite correct at any time. So if I
> have to convert the value of the sequence therefore I need
> a little time. In the meantime the value could have changed
> and my information is worthless.

> I think the best way would be to code a store procedure
> for the problem. Any ideas would be welcome.

You could use an ordinary sequence internally and translate the
sequential values to your representation on output, like that:

SELECT num / 36 ||
CASE
WHEN num % 36 < 10 THEN chr ((num % 36) + ascii ('0'))
ELSE chr ((num % 36) - 10 + ascii ('A'))
END

Me thinks this might be the most efficient way to deal with that.