Read from database {RPgSQL}R Documentation

Read query results into a data frame

Description

db.read.table reads a database table into a data frame.
db.fetch.result reads the contents of the query buffer into a data frame.
db.read.column returns a vector containing values from a given column in the result buffer.

Usage

db.read.table(name, row.names, col.names, as.is=F)
db.fetch.result(row.names, col.names, as.is=F)
db.read.column(column=1, as.is=F)

Arguments

name The name of a PostgreSQL table or a proxy object
row.names A list of row names to apply to the data frame
col.names A list of column names for the resulting data frame
as.is A boolean or vector of booleans or column indices specifying which character type columns should not be converted to factors
column The column number to read from the result buffer

Details

db.read.table simply queries the entire table and then calls db.fetch.result.
db.read.column does all the work; it is useful when you want the results to be a vector and not a data frame.

Value

db.read.table returns a data frame containing the data table.
db.fetch.result returns data frame containing the query results.
db.read.column returns a vector containing a single column of query output.

Author(s)

Timothy H. Keitt

See Also

db.write.table

Examples

if (db.connection.open()) {
  db.read.table('pg_user')
  db.execute('select usename, usesysid from pg_user', clear=F)
  db.fetch.result()
  db.read.column(column=2)
  db.clear.result()
}