SQLite {RSQLite} | R Documentation |
This function creates and initializes the SQLite engine. It returns an object that allows you to connect to the SQLite embedded engine.
SQLite(max.con = 16, fetch.default.rec = 500, force.reload = F)
max.con |
maximum number of connections that may be open at one time. This can be up to 100, a limit defined at compilation time. Note that since the SQLite engine is embedded (i.e., a set of C functions within the R/S-Plus process) connections consume very little resources. |
fetch.default.rec |
number of records to fetch at one time from the database.
(The fetch method uses this number as a default.)
|
force.reload |
should the package code be reloaded (reinitialized)?
Setting this to TRUE allows you to change
default settings. Notice that all connections should be closed
before re-loading.
|
This object is a singleton, that is, on subsequent invocations it returns the same initialized object.
This implementation allows the R/S-Plus embedded SQLite engine to work with multiple database instances through multiple connections simultaneously.
SQLite keeps each database instance in one single file. The name of the database is the file name, thus database names should be legal file names in the running platform.
An object of class SQLiteDriver
which extends
dbDriver
and
dbObjectId
.
This object is required to create connections
to the embedded SQLite database.
There can be many SQLite database instances running
simultaneously.
The R/S-Plus client part of the database communication is initialized,
but note that connecting to database instances needs to be done through
calls to dbConnect
.
SQLite is a single-user database engine, so it has no concept of a user.
See the Omega Project for Statistical Computing at http://www.omegahat.org and http://stat.bell-labs.com/RS-DBI for more details on the R/S-Plus database interface.
See the Adobe PDF file DBI.pdf
under the doc
subdirectory of the DBI package, i.e.,
system.file("doc", "DBI.pdf", package = "DBI")
See the documentation at the SQLite Web site http://www.hwaci/com/sw/sqlite/index.html for details.
David A. James
On database drivers:
dbDriver
SQLite
dbUnloadDriver
dbListConnections
On connections, SQL statements and resultSets:
dbConnect
dbDisconnect
dbSendQuery
dbGetQuery
fetch
dbListResults
On transaction management:
On meta-data:
summary
dbGetInfo
dbListTables
dbListFields
dbColumnsInfo
dbGetException
dbGetStatement
dbHasCompleted
dbGetRowCount
dbGetAffectedRows
# create a SQLite instance and create one connection. m <- dbDriver("SQLite") # initialize a new database "base.dbms" in the current directory # and copy some data.frame from the base package into it con <- dbConnect(m, dbname = "base.dbms") data(USArrests) dbWriteTable(con, "USArrests", USArrests, overwrite = T) # query rs <- dbSendQuery(con, "select * from USArrests") d1 <- fetch(rs, n = 10) # extract data in chunks of 10 rows dbHasCompleted(rs) d2 <- fetch(rs, n = -1) # extract all remaining data dbHasCompleted(rs) dbClearResult(rs) dbListTables(con)