Search Postgresql Archives

Re: not so sequential sequences

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



rhys.stewart@xxxxxxxxx ("Rhys Stewart") writes:
> Hi all, looking for a method to number a table sequentially, but the
> sequence only increments if the value in a certain column is
> different. as in
>
>
> seq    |   parish
> ------------------------
> 1      | Kingston
> 1      | Kingston
> 1      | Kingston
> 1      | Kingston
> 2      | Lucea
> 3      | Morant Bay
> 3      | Morant Bay
> 3      | Morant Bay
> 4      | Port Antonio
> 5      | Savannah-La-Mar
> 5      | Savannah-La-Mar
> 5      | Savannah-La-Mar
>
> so i guess i would order by a certain column and then the 'magic
> sequence' would be a column that only increments when the column
> changes.

The usual way to do this would be to separate out what clearly is a
dependant table; the seq and parish values could be associated with a
smaller table that increments any time you get a new parish.

The process of doing this sort of separation is called "normalization."
<http://en.wikipedia.org/wiki/Database_normalization>
-- 
(reverse (concatenate 'string "gro.mca" "@" "enworbbc"))
http://linuxfinances.info/info/internet.html
Rules of the Evil Overlord #32. "I will not fly into a rage and kill a
messenger who brings me bad news  just to illustrate how evil I really
am. Good messengers are hard to come by."
<http://www.eviloverlord.com/>


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux