Reads a database table to a data frame, optionally converting
a column to row names and converting the column names to valid
R identifiers.
Use dbReadTableArrow() instead to obtain an Arrow object.
DBI:::methods_as_rd("dbReadTable")
dbReadTable(conn, name, ...)dbReadTable() returns a data frame that contains the complete data
from the remote table, effectively the result of calling dbGetQuery() with
SELECT * FROM <name>.
An empty table is returned as a data frame with zero rows.
The presence of rownames depends on the row.names argument,
see sqlColumnToRownames() for details:
If FALSE or NULL, the returned data frame doesn't have row names.
If TRUE, a column named "row_names" is converted to row names.
If NA, a column named "row_names" is converted to row names if it exists,
otherwise no translation occurs.
If a string, this specifies the name of the column in the remote table that contains the row names.
The default is row.names = FALSE.
If the database supports identifiers with special characters,
the columns in the returned data frame are converted to valid R
identifiers
if the check.names argument is TRUE,
If check.names = FALSE, the returned table has non-syntactic column names without quotes.
A DBIConnection object, as returned by
dbConnect().
The table name, passed on to dbQuoteIdentifier(). Options are:
a character string with the unquoted DBMS table name,
e.g. "table_name",
a call to Id() with components to the fully qualified table name,
e.g. Id(schema = "my_schema", table = "table_name")
a call to SQL() with the quoted and fully qualified table name
given verbatim, e.g. SQL('"my_schema"."table_name"')
Other parameters passed on to methods.
An error is raised if the table does not exist.
An error is raised if row.names is TRUE and no "row_names" column exists,
An error is raised if row.names is set to a string and no corresponding column exists.
An error is raised when calling this method for a closed
or invalid connection.
An error is raised
if name cannot be processed with dbQuoteIdentifier()
or if this results in a non-scalar.
Unsupported values for row.names and check.names
(non-scalars,
unsupported data types,
NA for check.names)
also raise an error.
The following arguments are not part of the dbReadTable() generic
(to improve compatibility across backends)
but are part of the DBI specification:
row.names (default: FALSE)
check.names
They must be provided as named arguments. See the "Value" section for details on their usage.
The name argument is processed as follows,
to support databases that allow non-syntactic names for their objects:
If an unquoted table name as string: dbReadTable() will do the
quoting,
perhaps by calling dbQuoteIdentifier(conn, x = name)
If the result of a call to dbQuoteIdentifier(): no more quoting is done
This function returns a data frame.
Use dbReadTableArrow() to obtain an Arrow object.
Other DBIConnection generics:
DBIConnection-class,
dbAppendTable(),
dbAppendTableArrow(),
dbCreateTable(),
dbCreateTableArrow(),
dbDataType(),
dbDisconnect(),
dbExecute(),
dbExistsTable(),
dbGetException(),
dbGetInfo(),
dbGetQuery(),
dbGetQueryArrow(),
dbIsReadOnly(),
dbIsValid(),
dbListFields(),
dbListObjects(),
dbListResults(),
dbListTables(),
dbQuoteIdentifier(),
dbReadTableArrow(),
dbRemoveTable(),
dbSendQuery(),
dbSendQueryArrow(),
dbSendStatement(),
dbUnquoteIdentifier(),
dbWriteTable(),
dbWriteTableArrow()
if (FALSE) { # requireNamespace("RSQLite", quietly = TRUE)
con <- dbConnect(RSQLite::SQLite(), ":memory:")
dbWriteTable(con, "mtcars", mtcars[1:10, ])
dbReadTable(con, "mtcars")
dbDisconnect(con)
}
Run the code above in your browser using DataLab