Re: Function PostgreSQL 9.2

On Wed, Apr 20, 2016 at 2:51 PM, drum(dot)lucas(at)gmail(dot)com <drum(dot)lucas(at)gmail(dot)com>
wrote:

> 1 - The customer can add any value into users.code column
> 2 - The customer can chose between *add or no**t* add the value on
> users.code column
> 3 - If users.code is null (because the customer's chosen not to add any
> value in there), a trigger/function has to do the job.
> 4 - the function/trigger add the next available value, which the default
> is 1000 and it's stored on companies.client_code_increment
>
>
​And if the value you compute happens to be one the client choose
themselves what happens?

The procedural logic for this shouldn't be too complicated. The
documentation can give you syntax and capabilities.

The bigger problem is an ill-defined process and unexpected conflicts both
with the data itself (my comment above) and with concurrency.

I wouldn't give the user a choice. Either they always pick values or they
never pick values. I'd give them a function they can choose to utilize to
auto-generate values if they do not wish to select their own. Document the
algorithm and if they choose to mix-and-match they should avoid conflicting
algorithms.

I'd probably use CREATE SEQUENCE and pull numbers from that using nextval
instead of trying to code a custom sequence generator with meta-data stored
on a company column. I'd relax the "one sequence per company" behavior if
possible.

David J.