dhis2-devs team mailing list archive

[Lars Helge Øverland <larshelge@xxxxxxxxx>]

Hi Farai,

the categoryoptioncombo table is in fact very much part of the schema and
has foreign keys from the categoryoptioncombos_categoryoptions
and categorycombos_optioncombos join tables.

The point with category option combos is that we need a single foreign key
in the datavalue table which links it to the category model - this because
a data value can be linked to any number of category options and we cannot
have a dynamic number of columns/foreign keys in the datavalue table to
each of them. So the categoryoptioncombos represent a unique set of
category options, allowing a single row in a single table to be linked to a
data value.

regards,

Lars






On Mon, Aug 19, 2013 at 1:03 AM, Farai Mutero <fmutero@xxxxxxxxx> wrote:

> Hi All
>
> I've been taking a closer look at the object model for Categories and
> Category Combinations in Postgresql. While putting together the object
> model I noticed that the *categoryoptioncombo* table* *is not dependent
> on any other table in the database, yet contains critical values that are
> also referenced in the *datavalue* table.
>
> My questions is, why *categoryoptioncombos? *Why link a datavalue table
> row to a *categoryoptioncomboid* instead of a* dataelementcategoryoptionid
> *?
>
> Regards
>
> --
> Farai Mutero
>
>
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