R: Read and write MariaDB tables.

mariadb-tables {RMariaDB} | R Documentation

## Read and write MariaDB tables.

### Description

These methods read or write entire tables from a MariaDB database.

### Usage

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

    ## S4 method for signature 'MariaDBConnection,character,data.frame'
    dbWriteTable(
      conn,
      name,
      value,
      field.types = NULL,
      row.names = FALSE,
      overwrite = FALSE,
      append = FALSE,
      ...,
      temporary = FALSE
    )

    ## S4 method for signature 'MariaDBConnection,character,character'
    dbWriteTable(
      conn,
      name,
      value,
      field.types = NULL,
      overwrite = FALSE,
      append = FALSE,
      header = TRUE,
      row.names = FALSE,
      nrows = 50,
      sep = ",",
      eol = "\n",
      skip = 0,
      quote = "\"",
      temporary = FALSE,
      ...
    )

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

    ## S4 method for signature 'MariaDBConnection'
    dbListObjects(conn, prefix = NULL, ...)

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

    ## S4 method for signature 'MariaDBConnection,character'
    dbRemoveTable(conn, name, ..., temporary = FALSE, fail_if_missing = TRUE)

### Arguments

`conn` | a MariaDBConnection object, produced by `DBI::dbConnect()`
`name` | a character string specifying a table name.
`...` | Unused, needed for compatibility with generic.
`row.names` | Either `TRUE`, `FALSE`, `NA` or a string. If `TRUE`, always translate row names to a column called "row_names". If `FALSE`, never translate row names. If `NA`, translate rownames only if they're a character vector. A string is equivalent to `TRUE`, but allows you to override the default name. For backward compatibility, `NULL` is equivalent to `FALSE`.
`check.names` | If `TRUE`, the default, column names will be converted to valid R identifiers.
`value` | A data frame.
`field.types` | Optional, overrides default choices of field types, derived from the classes of the columns in the data frame.
`overwrite` | a logical specifying whether to overwrite an existing table or not. Its default is `FALSE`.
`append` | a logical specifying whether to append to an existing table in the DBMS. If appending, then the table (or temporary table) must exist, otherwise an error is reported. Its default is `FALSE`.
`temporary` | If `TRUE`, creates a temporary table that expires when the connection is closed. For `dbRemoveTable()`, only temporary tables are considered if this argument is set to `TRUE`.
`header` | logical, does the input file have a header line? Default is the same heuristic used by `read.table()`, i.e., `TRUE` if the first line has one fewer column that the second line.
`nrows` | number of lines to rows to import using `read.table` from the input file to create the proper table definition. Default is 50.
`sep` | field separator character
`eol` | End-of-line separator
`skip` | number of lines to skip before reading data in the input file.
`quote` | the quote character used in the input file (defaults to `\"`.)
`prefix` | A fully qualified path in the database's namespace, or `NULL`. This argument will be processed with `dbUnquoteIdentifier()`. If given the method will return all objects accessible through this prefix.
`fail_if_missing` | If `FALSE`, `dbRemoveTable()` succeeds if the table doesn't exist.

### Value

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

### Note

The data.frame returned by `dbReadTable()` only has primitive data, e.g., it does not coerce character data to factors. Temporary tables are ignored for `dbExistsTable()` and `dbListTables()` due to limitations of the underlying C API. For this reason, a prior existence check is performed only before creating a regular persistent table; an attempt to create a temporary table with an already existing name will fail with a message from the database driver.

### Examples

    if (mariadbHasDefault()) {
    con <- dbConnect(RMariaDB::MariaDB(), 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, ], temporary = TRUE)
    dbReadTable(con, "mtcars")
    dbReadTable(con, "mtcars", row.names = FALSE)
    }

[Package RMariaDB version 1.1.1 Index]