README.md

RODBCext

Travis-CI Build Status

Extension to the RODBC R package providing support for parameterized queries.

Parameterized queries are the kosher way of executing SQL queries when query string contain data from untrusted sources (especially user input).

See XKCD - Exploits of a Mom

Morover parametrized queries speed up query execution if it is repeated many times (because query planning is done only once).

Installation

From CRAN

In R, paste the following into the console:

install.packages('RODBCext')

From GitHub using devtools

Devtools package provide an easy way to install packages from the GitHub.

If you encounter problems during installation on a Linux, please check if this applies to you or switch to other installation method.

1) Obtain recent gcc, g++, and gfortran compilers. Windows users can install the Rtools suite while Mac users will have to download the necessary tools from the Xcode suite and its related command line tools (found within Xcode's Preference Pane under Downloads/Components); most Linux distributions should already have up to date compilers (or if not they can be updated easily). Windows users should include the checkbox option of installing Rtools to their path for easier command line usage.

2) Install the devtools package (if necessary). In R, paste the following into the console:

install.packages('devtools')

3) Install RODBCext from the Github source code.

devtools::install_github('zozlak/RODBCext')

From source via git

1) Obtain recent gcc, g++, and gfortran compilers (see above instructions).

2) Install the git command line tools.

3) Open a terminal/command-line tool. The following code will download the repository code to your computer, and install the package directly using R tools (Windows users may also have to add R and git to their path)

git clone https://github.com/zozlak/RODBCext.git
R CMD INSTALL RODBCext

ODBC source configuration

Try to enable support for SQLDescribeParam() in your ODBC drivers.

This is not necessary, but will speed up the query execution and lower a risk of unexpected types conversion.

Enabling support for SQLDescribeParam() depends on the driver, e.g.:

Usage

In parameterized queries, query execution is splitted into three steps:

  1. Query preparation, where database plans how to execute a query.
  2. Query execution, where database actually executes a query. If query has parameters, they are passed in this step.
  3. Fetching results (if there are any).

RODBC already has a functions responsible for the 3rd step - sqlGetResults(), sqlFetch(), sqlFetchMore(). RODBCext adds two functions responsible for the 1st and 2nd step:

  1. sqlPrepare()
  2. sqlExecute()

See examples:

library(RODBCext)
conn = odbcConnect("MyODBCSource")

# Run a parameterized query
sqlPrepare(conn, "SELECT * FROM table WHERE column1 = ? AND column2 = ?")
sqlExecute(conn, data=data.frame('column1value', 'column2value'))
sqlFetch(conn)
# one-call equivalent:
sqlExecute(
  conn, 
  query="SELECT * FROM table WHERE column1 = ? AND column2 = ?", 
  data=data.frame('column1value', 'column2value'), 
  fetch=TRUE
)

# Insert many rows into the table:
sqlPrepare(conn, "INSERT INTO table (charColumn, intColumn) VALUES (?, ?)")
sqlExecute(conn, data=data.frame(c('a', 'b', 'c'), 1:3))
# one-call equivalent:
sqlExecute(
 conn, 
 query="INSERT INTO table (charColumn, intColumn) VALUES (?, ?)", 
 data=data.frame(c('a', 'b', 'c'), 1:3)
)

# Run query without parameters:
sqlPrepare(conn, "SELECT * FROM table")
sqlExecute(conn)
sqlFetch(conn)
# one-call equivalent:
sqlExecute(conn, query="SELECT * FROM table", fetch=TRUE)



Try the RODBCext package in your browser

Any scripts or data that you put into this service are public.

RODBCext documentation built on July 31, 2017, 9:01 a.m.