On Dec 21, 2007, at 1:36 PM, Mike McGonagle wrote:

On 12/21/07, Mathieu Bouchard <matju@artengine.ca> wrote:
On Tue, 18 Dec 2007, Mike McGonagle wrote:

> [query <srv_id> insert into mytable (id, name, token) values (?f,'?s','?s')]
> In this example, the first placeholder would expect a Float, with the next
> two expecting a Symbol (just think of this as a variation on the printf
> string substitutions).

It looks more like the types of [t] [pack] [unpack] [expr] etc.

Yes, they are PD types.

You don't really need to type your data. SQL is largely typeless: at least
at the level of what you can put in one table cell, anything is a string.
It becomes typed (but auto-cast) when put in the cell, but rebecomes
untyped when taken out of the cell.

Yes, I know that these things can be stored in a typeless manner, but the functions that bind the SQL statement with their placeholders can be of any type, as there are functions for the various datatypes.

http://www.sqlite.org/c3ref/bind_blob.html

This link shows all the different functions used to bind the data to the statement placeholders.

http://dev.mysql.com/doc/refman/5.0/en/c-api-prepared-statement-datatypes.html

And if you look at how MySQL does this, while they only provide a single bind function, it does have the datatypes for the data in a structure that gets passed into the bind function.

Also, from looking at libdbi, it appears that they don't even bother with placeholders at all.

I don't know whether Perl DBI is the same as libdbi, but Perl DBI definitely uses placeholders:

http://www.stupidfool.org/perl/docs/perltut/dbi/dbiplace.html

This is not an issue of how the user sees these things, it is how the C code interfaces with the database.

So, just how do we do this in a consistent manner when all the different interfaces don't support these things, AND if they do, they do them differently.

We just need a clearly defined standard, then each object will handle the translation. We can look at code like Perl:DBI for an examples of how thing could be done. That might even be in C, so we could use that code.

> but considering that the databases need to know the specific data types
> for each placeholder,

heh? do they?

SQLite does. MySQL appears to as well. And yes, it is possible to just force everything to be a string/c-string and be done with it. SQLite actually stores everything as a string anyway, despite the defined types in the create statement.

We can get the type info from the Pd type system if we need it. That will give us symbols and floats.

.hc

Mike

_ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard - tél:+1.514.383.3801, Montréal QC Canada

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