Hi, Here is an example of paste:
> paste("and", 1:3, collapse = " ")
[1] "and 1 and 2 and 3"
in which and was prepended to each of the vector entries and then
everything was collapsed together. In our
situation we don't actually want the first 'and' so we substitute for
it, using sub,
the first portion of the SQL statement.
Suggest you turn on debugging:
debug(retrieve) # undebug(retrieve) will turn it back off
and run the function and at each try printing out various partial
expressions to see what they do.
Regards.
On 6/19/06, Alex Restrepo <[EMAIL PROTECTED]> wrote:
> Hi Gabor:
>
> Thanks for the great example. I am an R newbie, so please forgive my
> question, but
> could you describe what the sub() function is doing in your example? Why is
> there an "and" in the first argument to the sub() function?
>
>
> Many Thanks:
>
> Alex
>
>
> >From: "Gabor Grothendieck" <[EMAIL PROTECTED]>
> >To: "Alex Restrepo" <[EMAIL PROTECTED]>
> >CC: [email protected]
> >Subject: Re: [R] Custom Command to Generate SQL
> >Date: Mon, 19 Jun 2006 01:21:53 -0400
> >
> >This generates the sql statement so just pass that to your database:
> >
> >retrieve <- function(...) {
> > args <- list(...)
> > sub("and", "select * from people where",
> > paste(rbind("and", names(args), "=", dQuote(args)), collapse = " "))
> >}
> >
> ># test
> >retrieve(firstname = "JOHN", middlename = "WILLIANS", lastname = "FORD")
> >
> >On 6/19/06, Alex Restrepo <[EMAIL PROTECTED]> wrote:
> >>Hi:
> >>
> >>I would like to create a custom command in R which generates SQL, which is
> >>then processed via RODBC.
> >>
> >>For example, the user would type:
> >>
> >> retrieve firstName('JOHN') middlleName('WILLIAMS')
> >>lastName('FORD')
> >>
> >>This would generate the following SQL which would then be processed by
> >>RODBC:
> >>
> >>Select *
> >> from people
> >> where firstName = 'JOHN' and
> >> middleName = 'WILLIAMS' and
> >> lastName = 'FORD'
> >>
> >>Does anyone have a recommendation? Any ideas would be greatly
> >>appreciated.
> >>
> >>Alex
> >>
> >>______________________________________________
> >>[email protected] mailing list
> >>https://stat.ethz.ch/mailman/listinfo/r-help
> >>PLEASE do read the posting guide!
> >>http://www.R-project.org/posting-guide.html
> >>
>
>
>
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