Reads a database table to a data frame, optionally converting a column to row names and converting the column names to valid R identifiers.

dbReadTable(conn, name, ...)

Arguments

conn

A DBIConnection object, as returned by dbConnect().

name

A character string specifying the unquoted DBMS table name, or the result of a call to dbQuoteIdentifier().

...

Other parameters passed on to methods.

Value

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 error is raised if the table does not exist. 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, an error is raised if no such column exists.

  • 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, an error is raised if no such column exists.

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, otherwise non-syntactic column names can be returned unquoted.

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.

Additional arguments

The following arguments are not part of the dbReadTable() generic (to improve compatibility across backends) but are part of the DBI specification:

  • row.names

  • check.names

They must be provided as named arguments. See the "Value" section for details on their usage.

Specification

The name argument is processed as follows, to support databases that allow non-syntactic names for their objects:

See also

Other DBIConnection generics: DBIConnection-class, dbDataType, dbDisconnect, dbExecute, dbExistsTable, dbGetException, dbGetInfo, dbGetQuery, dbIsValid, dbListFields, dbListResults, dbListTables, dbRemoveTable, dbSendQuery, dbSendStatement, dbWriteTable

Examples

con <- dbConnect(RSQLite::SQLite(), ":memory:") dbWriteTable(con, "mtcars", mtcars[1:10, ]) dbReadTable(con, "mtcars")
#> mpg cyl disp hp drat wt qsec vs am gear carb #> 1 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4 #> 2 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4 #> 3 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 #> 4 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1 #> 5 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2 #> 6 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1 #> 7 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4 #> 8 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2 #> 9 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2 #> 10 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4