Re: Issuing standard SQL commands from clients

[Rodrigo Moya Piernavieja <rmoya tsai es>]

Vivien Malerba wrote:

> On jeu, 10 fév 2000, Rodrigo Moya Piernavieja wrote:
>
> >
> > Well, reading through this mail, I've remembered a problem I found when
> > implementing the new XML stuff, which is: how can I issue standard SQL commands
> > (such as "select * from table" or "update ....") in a way understable by all the
> > providers? because there are placesin the GDA libs
> > (gda_xml_table_new_from_gda_recordset and this GnomeDbReport) where you must
> > issue these commands. The first thing that comes to my mind is to use standard
> > SQL (SQL92 or something like that?), but, what will happen with no-DBMS providers
> > (LDAP, XML, ...)? and maybe standard SQL means less flexibility for some
> > providers that do have extra stuff.
> >
>
> There might be the possibility to use a tree structure to make a request. I
> think every DBMS uses an internal structure to represent a query. It is a
> structure (and can be a tree of structures) which can represent any operation
> the DBMs can do. Why wouldn't we use the same technique, that is the client
> builds the structure he wants, and gives it to the provider which is in charge
> of converting that structure to SQL statements (or whatever...).
>
> The advantages I see in this method are:
> - it can be easily extended to non DBMS providers.
> - it can use all the extra stuff that some providers can have.
> - it is flexible.
> - it is possible to use XML to convert any of these structs to text (to save
> it, or even to feed the provider so that no IDL modification is necessary).
>
> If you think it a good idea, I can have a look at how the Postgres DBMS uses
> these structures and trees.
>

Perfect, this is a great idea, please tell us as soon as you've got something!