| dbReadTable-methods {RSQLite} | R Documentation |
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.
A data.frame in the case of dbReadTable; otherwise a logical
indicating whether the operation was successful.
SQLiteConnection database connection object.
value is a character, it is interpreted as a
file name and its contents imported to SQLite.
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).
FALSE. (See the BUGS section below).
FALSE.
When dbWriteTable is used to import data from a file,
you may optionally specify header=, row.names=,
col.names=, sep=, eol=, field.types=,
and skip=.
header is a logical indicating whether the first data line
(but see skip) has a header or not. If missing, it value
is determined following read.table convention,
namely, it is set to TRUE if and only if the first row has one
fewer field that the number of columns.
row.names is a logical to specify whether the first column
is a set of row names. If missing its defualt follows the
read.table convention.
col.names a character vector with column names (these names
will be filtered with make.db.names to
ensure valid SQL identifiers. (See also field.types below.)
The field separator sep= defaults to ','.
The end-of-line delimiter eol defaults to '\n'.
skip specifies number of lines to skip before reading the data
and it defaults to 0.
field.types is a list of named field SQL types where
names(field.types) provide the new table's column names
(if missing, field types are inferred using dbDataType).
These RSQLite methods do not use transactions, thus it is dangerous
to specify overwrite=TRUE in dbWriteTable (the
table is first removed and in case the data exporting fails
the original table is lost forever).
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.
See the Database Interface definition document
DBI.pdf in the base directory of this package
or http://stat.bell-labs.com/RS-DBI.
sqliteImportFile,
SQLite,
dbDriver,
dbConnect,
dbSendQuery,
dbGetQuery,
fetch,
dbCommit,
dbGetInfo,
dbListTables,
dbReadTable.
## Not run:
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)
}
## End(Not run)