query: PostgreSQL query

In rpg: Easy Interface to Advanced PostgreSQL Features

Description

Issue a query to the current database connection

Usage

result_dim()

get_tuple_info()

query(sql = "", pars = NULL)

query_error()

fetch(sql = "", pars = NULL)

execute(...)

Arguments

sql	a query string
pars	a character vector of substitution values
...	list of commands to be pasted together

Details

fetch returns the result of a query as a data frame. If sql is NULL or empty, then an attempt will be made to retrieve any pending resutls from previous queries. Note that query results are not cleared until the next query is issued so fetch will continue to return results until a new query is issued.

execute is a wrapper around query. It will raise an exception if the command does not complete. Exceptions can be caught with tryCatch. You cannot use a parameterized query with execute. Unlike query it will paste its arguments into a single string.

Value

result_dim returns the number of tuples and fields

get_tuple_info returns an integer array with tuple information.

query returns:

PGRES_EMPTY_QUERY	The string sent to the server was empty
PGRES_COMMAND_OK	Successful completion of a command returning no data
PGRES_TUPLES_OK	Successful completion of a command returning data (such as a SELECT or SHOW)
PGRES_COPY_OUT	Copy Out (from server) data transfer started
PGRES_COPY_IN	Copy In (to server) data transfer started
PGRES_BAD_RESPONSE	The server's response was not understood.
PGRES_NONFATAL_ERROR	A nonfatal error (a notice or warning) occurred
PGRES_FATAL_ERROR	A fatal error occurred
PGRES_COPY_BOTH	Copy In/Out (to and from server) data transfer started. This is currently used only for streaming replication

query_error returns an error string

fetch returns a data frame or a query status object on failure.

execute the result status string

Author(s)

Timothy H. Keitt

See Also

psql

Examples

## Not run: 
createdb("rpgtesting")
connect("rpgtesting")
begin()
execute("DROP SCHEMA IF EXISTS rpgtesting CASCADE")
execute("CREATE SCHEMA rpgtesting")
execute("SET search_path TO rpgtesting")
execute("DROP TABLE IF EXISTS test")
execute("CREATE TABLE test (id integer, field text)")
query("INSERT INTO test VALUES ($1, $2)", c(1, "test"))
fetch("SELECT * FROM test")
result_dim()
fetch("SELECT * FROM testing")
query_error()
rollback()
disconnect()
dropdb("rpgtesting")
## End(Not run)

rpg documentation built on May 2, 2019, 5:14 a.m.