[PD-dev] Fwd: Fwd: Fwd: Fwd: Connecting up an SQL Database to PD

[Mike McGonagle]

???

---------- Forwarded message ----------
From: Mike McGonagle <mjmogo at gmail.com>
Date: Nov 13, 2007 11:57 AM
Subject: Re: [PD-dev] Fwd: Fwd: Fwd: Connecting up an SQL Database to PD
To: jamie at postlude.co.uk


Jamie,

After looking at you code for passing messages into the external,
instead of on the creation args, I agree, this is a little more
elegant of a design.

That being said, I did notice a couple of things that might result is
very subtle bugs.

1. Suppose we have a statement like this...

sql select onset, pitch, velocity, 1, duration from myscore endsql

Not having been able to compile your external, I am not quite certain,
but I think in this case there would be 5 different messages sent to
the external as follows:

a. sql select onset
b. pitch
c. velocity
d. 1
e. duration from myscore endsql

as this stands, the first a, b, and c would be passed through the
'anything' method. But as d is NOT a list, it would pass through the
'float' method, and the remainder would pass through the 'anything'.
As your code is right now, I think the 4th thing would get dropped.
Now I know this is probably not all that common, but consider the case
where a sequence is stored in the database, and the user wants to
create a variation of how it gets rendered, and wants one of those
parameters to be a CONSTANT. As it is legal SQL to pass in a literal
number on the 'select' columns list, this CONSTANT can be substituted
for the parameter in the database.

2. Class methods such as 'close'. As you are depending on the
'anything' method to gather up things that are not actually recognized
by the external and assume they are SQL, if by chance, there was a
field that the user wanted to extract from the database that is named
'close', it would fail.

sql select id, name, close from table endsql

a. sql select id
b. name
c. close

this would only process things upto and including the close. Also, any
other class messages that you create would have the same effect.

To get around this, I would think that there should be a single
symbol, maybe using the class name (or something), which would then be
followed by the actual option.

I wrote a test external last night to test these things, and if you
are interested, I could send this to you. I will have to do that
tomorrow, as I don't have my computer with me at work.

Mike

On 11/13/07, Jamie Bullock <jamie at postlude.co.uk> wrote:
>
> On Mon, 2007-11-12 at 16:51 -0600, Mike McGonagle wrote:
> > On 11/12/07, Jamie Bullock <jamie at postlude.co.uk> wrote:
> > > I'm sure you've already looked at it, but there's a (maybe) useful
> > > README and help file here:
> > >
> > > http://pure-data.cvs.sourceforge.net/pure-data/externals/postlude/psql/
> >
> > Jamie,
> >
> > I was looking at your source code for psql,
>
> I know I said this already, and it's in the sources, but just for the
> record, the majority of the code in [psql] is by Iain Mott. I just
> forked the code added a little functionality, and took over maintaining
> it in CVS.
>
> > and was wondering if it
> > expects there to be only a single result set returned? Or does it
> > merge all the results into one? I noticed the the comment...
> >
>
> It gathers the results from each query and prefixes them with an index
> starting from 0, outputting each row as a list.
>
> > /*  up to 10 fields may be returned. returns floats or symbols */
>
> This is referring to the number of columns (not rows) that may be
> returned (corresponding to atoms in each Pd list from the outlet).
> There's no reasoon why this figure can't be higher, so I might change
> this in the source.
>
> > I would think that making it such that it acted like 'textfile', that
> > with each bang sent to the sql object, that it would return each
> > subsequent row, and once the end of that set is reached, it would
> > output a bang on a second outlet, similar to what 'textfile' does.
> >
>
> Good idea! I'll add that too.
>
> Jamie
>
> --
> www.postlude.co.uk
>
>


--
Help the Environment, Plant a Bush back in Texas!

"I place economy among the first and most important republican
virtues, and public debt as the greatest of the dangers to be feared.
To preserve our independence, we must not let our rulers load us with
perpetual debt."
-- Thomas Jefferson, third US president, architect and author (1743-1826)

"Give Peace a Chance" -- John Lennon (9 October 1940 – 8 December 1980)

Peace may sound simple—one beautiful word— but it requires everything
we have, every quality, every strength, every dream, every high ideal.
—Yehudi Menuhin (1916–1999), musician

If you think you can, or you think you can't, you are probably right.
—Mark Twain

"Art may imitate life, but life imitates TV."
Ani DiFranco


-- 
Help the Environment, Plant a Bush back in Texas!

"I place economy among the first and most important republican
virtues, and public debt as the greatest of the dangers to be feared.
To preserve our independence, we must not let our rulers load us with
perpetual debt."
-- Thomas Jefferson, third US president, architect and author (1743-1826)

"Give Peace a Chance" -- John Lennon (9 October 1940 – 8 December 1980)

Peace may sound simple—one beautiful word— but it requires everything
we have, every quality, every strength, every dream, every high ideal.
—Yehudi Menuhin (1916–1999), musician

If you think you can, or you think you can't, you are probably right.
—Mark Twain

"Art may imitate life, but life imitates TV."
Ani DiFranco