Desktop Survival Guide
by Graham Williams
Data can be sourced from many diverse repositories. Data is often stored today in relational databases like Oracle, MySQL, and SQLite, and accessed by the structured query language (SQL). It could be stored in systems like SAS and many other alternative proprietary systems. Many such systems provide access to the data in a number of forms and have particularly well tuned and efficient procedures for accessing the data. Such access is fine for many applications, but the user tends to be limited to the functionality provided by the particular application environment.
R provides a wealth of tools for importing data. In this section we overview the functions used to access common data formats. For a more complete exposition see 05:r_data_impor_expor.
OLTP systems such as billing systems
Special databases, such as marketing and sales
External data sources, e.g., demographic data, market survey data
Describe output variable and input variables.