Re: [gnome-db] GdaSqlBuilder and WHERE clauses

On 27 April 2010 18:03, Murray Cumming <[email protected]> wrote:
> In Glom, I have several generic functions that combine a fixed SQL query
> with various WHERE clauses. Imagine something like this
>
>  DataModel get_data_from_table(string where_clause)
>
> It does this by doing a simple string concatenation.
>
> But how can I do this with SqlBuilder, whose gda_sql_builder_add_cond()
> expects the details of the condition in terms of arguments and
> operator?:
> http://library.gnome.org/devel/libgda/unstable/GdaSqlBuilder.html#gda-sql-builder-add-cond
>
> Ideally, I think I'd have a GdaSqlBuilderCond object that I could pass
> around and even AND with another GdaSqlBuilderCond.

So if I understand you'd like to have a function as:
DataModel get_data_from_table(GdaSqlBuilderCond where_clause)

I would prefer to avoid creating a new object just for this case, and
prefer to add more flexibility to the GdaSqlBuilder by allowing the
import/export of parts of a statement (as an opaque GdaSqlAnyPart
pointer):

GdaSqlAnyPart *gda_sql_builder_export_part (GdaSqlBuilder *b, guint id);
and
guint gda_sql_builder_import_part (GdaSqlBuilder *b, guint id,
GdaSqlAnyPart *part);

With these 2 new calls you can create a
DataModel get_data_from_table(GdaSqlAnyPart where_clause):

1- create a GdaSqlBuilder with the where clause you want
2- export that WHERE clause as a GdaSqlAnyPart, and use it as argument
to your get_data_from_table() function
3- create a new GdaSqlBuilder with the specific SQL you need
4- import the GdaSqlAnyPart into that builder object
5- get the GdaStatement and execute it.
6- discard the unneeded objects

How does it sound?

Vivien