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% $Id: fetch-methods.Rd,v 0.1 2008/07/23 02:38:31 psk Exp $
\name{fetch-methods}
\docType{methods}
\alias{fetch-methods}
\alias{fetch,PostgreSQLResult,numeric-method}
\alias{fetch,PostgreSQLResult,missing-method}
%\alias{fetch,PostgreSQLResult-method}
\title{
Fetch records from a previously executed query
}
\description{
This method is a straight-forward implementation of the corresponding
generic function.
}
\section{Methods}{\describe{
\item{res}{
an \code{PostgreSQLResult} object.
}
\item{n}{
maximum number of records to retrieve per fetch.
Use \code{n = -1} to retrieve all pending records;
use a value of \code{n = 0} for fetching the default number
of rows \code{fetch.default.rec} defined in the
\code{\link{PostgreSQL}} initialization invocation.
}
\item{\dots }{currently not used.}
}
}
\details{
The \code{RPostgreSQL} implementations retrieves only \code{n} records,
and if \code{n} is missing it only returns up to \code{fetch.default.rec}
as specified in the call to \code{\link{PostgreSQL}} (500 by default).
}
\references{
See the Database Interface definition document
\code{DBI.pdf} in the base directory of this package
or \url{https://cran.r-project.org/package=DBI}.
}
\seealso{
\code{\link{PostgreSQL}},
\code{\link[DBI]{dbConnect}},
\code{\link[DBI]{dbSendQuery}},
\code{\link[DBI]{dbGetQuery}},
\code{\link[DBI]{dbClearResult}},
\code{\link[DBI]{dbCommit}},
\code{\link[DBI]{dbGetInfo}},
\code{\link[DBI]{dbReadTable}}.
}
\examples{\dontrun{
drv <- dbDriver("PostgreSQL")
con <- dbConnect(drv, user = "ruser",password = "123456",dbname = "status")
res <- dbSendQuery(con, statement = paste(
"SELECT w.category, w.cost, p.type",
"FROM items w, sales P",
"WHERE w.category = p.type",
"ORDER BY w.cost"))
# we now fetch the first 100 records from the resultSet into a data.frame
data1 <- fetch(res, n = 100)
dim(data1)
dbHasCompleted(res)
# let's get all remaining records
data2 <- fetch(res, n = -1)
}
}
\keyword{methods}
\keyword{interface}
\keyword{database}
% vim: syntax=tex
|
