Re: Table with Field Serial - Problem

Adrian Klaver <adrian.klaver@xxxxxxxxx> · Thu, 31 Oct 2013 10:05:21 -0700

On 10/31/2013 09:32 AM, David Johnston wrote:
Adrian Klaver-3 wrote
Table1
   Column  |       Type        |                          Modifiers
----------+-------------------__+-----------------------------__------------------------------__--
   id   | integer           | not null default
nextval('test_table_id_fld___seq'::regclass)

Table2
Column  |       Type        |                      related
----------+-------------------__+-----------------------------__------------------------------__--
   id_table1   | integer           |  FK of Table1.id
   id_lang       | integer          |  FK of lang.id
&lt;http://lang.id&gt;
   name         |  varchar

The PK for table 2 is composite: the serial key from table 1 + the language
id.  The table 1 id has to be able to repeat since the same "entity" needs
multiple translations.  Using a serial on table 2 is also possible but a
separate issue and probably not worth adding since you need a unique index
on (id_table1, id_lang) regardless.

The question is why isn't there some kind of identifier on table 1 that
gives you some idea of what the id/table record is for?

Exactly the id_table1 FK has no context, it is just a number generator, 
so why make it separate? If want to just generate numbers why not just 
use the sequence directly?

David J.

--
Adrian Klaver
adrian.klaver@xxxxxxxxx

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