chris,
if you could create a package similar to proc sql in SAs, that will be so sweet.
On 2/12/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> Hi R-users,
>
> This note will interest people who would like to use sql statements on R data
> frames (a bit like proc sql in SAS). Please reply to my only, unless you
> really want to keep the entire R-help list posted on this.
>
> I've been thinking about a packgage implementing sql queries in R. I'm almost
> about starting to write it in a very rudimentary version. What I have in mind
> is the following:
>
> Work in two ways:
> via a generic sql("..") wrapper which allows a generic query statement
> and via convenience functions, such as SELECT("..."), ...
> what would be needed is an "sqlTable" class extending the data frame. This
> class will have to have extra slots for indices and some other stuff. I would
> try to stay very basic in the beginning and also use relatively inefficient
> handling of the tables. Later-on, direct calls using the binary
> representations could replace the high level handling.
>
> Now come my questions:
> - have others started working on this?
> - are others interested in this?
> - ideas on how to go about it?
>
> Chris
>
> P.S.:
> Here are a few ideas I was thinking about
> One way would be to incorporate a gpl or lgpl rdbms into the package, to push
> the data-frame to it, to execute the statement there and to get the result
> back. The advantage: fast to implement. The disadvantage: pushing the data is
> a bad idea (but then again, at the top level, R will make a copy of it
> anyway, most probably). The convenience wrappers would then construct sql
> statements and the db engine would evaluate them.
>
> The other idea is to stay in R and to link the wrappers to adequately
> composed calls to subset, cbind, rbind, etc. Here it would be more
> challenging to create the sql("..") interface since its string would have to
> be parsed.
>
> The political incorrect thing about these SQL functions is that they (UPDATE,
> INSERT) will have to modify objects within the function call. They would not
> work via the return object.
>
> As I said, comments welcome.
>
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--
WenSui Liu
A lousy statistician who happens to know a little programming
(http://spaces.msn.com/statcompute/blog)
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