Re: [gnome-db] libgda escape_value() and schema retreival

["Murray Cumming" <murrayc murrayc com>]

>>This seems to add a function like this:
>>
>>gboolean
>>gda_connection_escape_string (GdaConnection *cnc,
>>			      gchar *from,
>>			      const gchar *to,
>>			      unsigned long length)
>
>>1. Why do we need to provide the length of the "from" string? Surely, all
>>strings in libgda are null-terminated?
>>
>>
> Sorry dont know libgda that well to comment..

It looks wrong. Rodrigo?

>>2. It seems to convert from "to" to "from". Isn't that a bit backwards?
>>
>>
> Actually, it was a pretty straight copy from the original mysql_/pgsql_
> functions that did the same thing.

I doubt that - could you show us the function signature for those
functions, please? Maybe someone just put the const in the wrong place.

> - the only justification for keeping
> that standard was probably that anyone who's familar with the API's
> would pick up libgda a minute bit faster..
>
>>3. Is this just for creating SQL-representations of text values? Surely
>>it's more useful to have a funciton to create a SQL representation of a
>>GValue, whatever type that GValue has.
>>
>>
> I agree, That would be better, In reality though, it's only strings
> AFAIK that need escaping, and may be locale specific on the database
> (eg. BIG5 in a mysql db, has to watch out what it quotes..) so if it was
> implemented as a Gda_connection_value_to_Sql(Gda_connection,
> Gda_value,gchar) - only when the gda_value was a string, would the
> function be called.

Well,
3.1: I'd like this function to add the quotes (I consider that part of
"escaping"), so it wouldn't just be strings that had quotes.

3.2: The function would need to create a text representation for numbers,
dates, and times, so it would do something. This would remove lots of
duplicated code in applications.

Also, it should create the text representation in the canonical locale (I
believe that the SQL specification says that it should be the C locale,
even if the database backend chooses to store them in some other locale).
Otherwise, the application has to do the work of creating an appropriate
C-locale text representation for times, dates and numbers. That's not
always easy.

>>4. Does this add the quotes, or do you need a big switch/case (switching
>>on the field type) block in the app for that?
>>
>>
>  actually, only a few types varchar/char/text need escaping (which are
> represented as a single type in gda? AFAIK), so it's not that huge a
> switch/case.

4. was not about escaping of text fields, but about quotes. Not just text
fields need quotes, or text representations, in SQL. For instance, I think
dates needs quotes, and they need to be a text representation in the C
locale.


Murray Cumming
murrayc murrayc com
www.murrayc.com
www.openismus.com