Convenience functions for Importing/Exporting DBMS tables

Description

These functions mimic their R/S-Plus counterpart get, assign, exists, remove, and objects, except that they generate code that gets remotely executed in a database engine.

Value

A data.frame in the case of dbReadTable; otherwise a logical indicating whether the operation was successful.

Methods

conn

an SQLiteConnection database connection object.

name

a character string specifying a table name.

value

a data.frame (or coercible to data.frame).

row.names

in the case of dbReadTable, this argument can be a string or an index specifying the column in the DBMS table to be used as row.names in the output data.frame (a NULL, "", or 0 specifies that no column should be used as row.names in the output).

In the case of dbWriteTable, this argument should be a logical specifying whether the row.names should be output to the output DBMS table; if TRUE, an extra field whose name will be whatever the R/S-Plus identifier "row.names" maps to the DBMS (see make.db.names).

overwrite

a logical specifying whether to overwrite an existing table or not. Its default is FALSE.

append

a logical specifying whether to append to an existing table in the DBMS. Its default is FALSE.

...

any optional arguments.

Note

Note that the data.frame returned by dbReadTable only has primitive data, e.g., it does not coerce character data to factors.

SQLite table names are not case sensitive, e.g., table names ABC and abc are considered equal.

References

See the Database Interface definition document DBI.pdf in the base directory of this package or http://developer.r-project.org/db.

See Also

SQLite, dbDriver, dbConnect, dbSendQuery, dbGetQuery, fetch, dbCommit, dbGetInfo, dbListTables, dbReadTable.

Examples

conn <- dbConnect("SQLite", dbname = "sqlite.db")
if(dbExistsTable(con, "fuel_frame")){
   dbRemoveTable(conn, "fuel_frame")
   dbWriteTable(conn, "fuel_frame", fuel.frame)
}
if(dbExistsTable(conn, "RESULTS")){
   dbWriteTable(conn, "RESULTS", results2000, append = T)
else
   dbWriteTable(conn, "RESULTS", results2000)
}