dbReadTable: Convenience functions for importing/exporting DBMS tables

Description Usage Arguments Value Note Examples

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.

Usage

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## S4 method for signature 'MySQLConnection,character'
dbReadTable(conn, name, row.names, check.names = TRUE, ...)

## S4 method for signature 'MySQLConnection'
dbListTables(conn, ...)

## S4 method for signature 'MySQLConnection,character'
dbExistsTable(conn, name, ...)

## S4 method for signature 'MySQLConnection,character'
dbRemoveTable(conn, name, ...)

## S4 method for signature 'MySQLConnection,character'
dbListFields(conn, name, ...)

Arguments

conn

a MySQLConnection object, produced by dbConnect

name

a character string specifying a table name.

row.names

A string or an index specifying the column in the DBMS table to use as row.names in the output data.frame. Defaults to using the row_names column if present. Set to NULL to never use row names.

check.names

If TRUE, the default, column names will be converted to valid R identifiers.

...

Unused, needed for compatiblity with generic.

Value

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

Note

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

Examples

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if (mysqlHasDefault()) {
con <- dbConnect(RMySQL::MySQL(), dbname = "test")

# By default, row names are written in a column to row_names, and
# automatically read back into the row.names()
dbWriteTable(con, "mtcars", mtcars[1:5, ], overwrite = TRUE)
dbReadTable(con, "mtcars")
dbReadTable(con, "mtcars", row.names = NULL)
}

Example output

Loading required package: DBI
Could not initialise default MySQL database. If MySQL is running
check that you have a ~/.my.cnf file that contains a [rs-dbi] section
describing how to connect to a test database.

RMySQL documentation built on June 22, 2021, 5:08 p.m.

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