1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
|
% $Id: dbDriver-methods.Rd,v 0.1 2008/07/28 01:09:05 psk Exp $
\name{dbDriver-methods}
\docType{methods}
\alias{dbDriver-methods}
\alias{dbUnloadDriver-methods}
\alias{dbDriver,character-method}
\alias{dbUnloadDriver,PostgreSQLDriver-method}
\title{
PostgreSQL implementation of the Database Interface (DBI) classes
and drivers
}
\description{
PostgreSQL driver initialization and closing
}
\section{Methods}{\describe{
\item{drvName}{
character name of the driver to instantiate.
}
\item{drv}{
an object that inherits from \code{PostgreSQLDriver} as created by
\code{dbDriver}.
}
\item{max.con}{optional integer requesting the maximum number of
simultanous connections (may be up to 100)}.
\item{fetch.default.rec}{default number of records to retrieve per fetch.
Default is 500. This may be overridden in calls to \code{\link[DBI]{fetch}}
with the \code{n=} argument.}
\item{force.reload}{optional logical used to force re-loading or recomputing
the size of the connection table. Default is \code{FALSE}.}
\item{...}{currently unused.}
}
}
\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]{fetch}},
\code{\link[DBI]{dbCommit}},
\code{\link[DBI]{dbGetInfo}},
\code{\link[DBI]{dbListTables}},
\code{\link[DBI]{dbReadTable}}.
}
\examples{\dontrun{
# create an PostgreSQL instance and set 10000 of rows per fetch.
library(RPostgreSQL)
drv <- dbDriver("PostgreSQL", fetch.default.records=10000)
# Connecting to PostgreSQL with the specified parameters
con <- dbConnect(drv,user="usrname",password="passwd",dbname="postgres")
# Running the query to obtain the resultset
rs <- dbSendQuery(con, "select * from cities where population > 5000")
# fetch records into a dataframe.
# n = 50 fetched fifty records
df <- fetch(rs, n = 50)
# n = -1 fetches all the remaining records available
df2 <- fetch(rs, n = -1)
# Clearing the result set
dbClearResult(rs)
#This returns a character vector (possibly of zero-length)
# table names available on the con connection.
dbListTables(con)
}
}
\keyword{methods}
\keyword{interface}
\keyword{database}
% vim: syntax=tex
|
