sqldf: SQL select on R data frames

sqldf is an R package for runing SQL statements on R data frames, optimized for convenience. The user simply specifies an SQL statement in R using data frame names in place of table names and a database with appropriate table layouts/schema is automatically created, the data frames are automatically loaded into the database, the specified SQL statement is performed, the result is read back into R and the database is deleted all automatically behind the scenes making the database's existence transparent to the user who only specifies the SQL statement. Surprisingly this can at times be faster than the corresponding pure R calculation (although the purpose of the project is convenience and not speed). sqldf is free software published under the GNU General Public License that can be downloaded from CRAN.