DBI-wrap function

DBI methods (simple wrappers)

These pool method for DBI generics methods check out a connection (with poolCheckout()), re-call the generic, then return the connection to the pool (with poolReturn()). See DBI-custom for DBI methods that do not work with pool objects.

## S4 method for signature 'Pool'
dbDataType(dbObj, obj, ...)

## S4 method for signature 'Pool,ANY'
dbGetQuery(conn, statement, ...)

## S4 method for signature 'Pool,ANY'
dbExecute(conn, statement, ...)

## S4 method for signature 'Pool,ANY'
dbListFields(conn, name, ...)

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

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

## S4 method for signature 'Pool,ANY'
dbReadTable(conn, name, ...)

## S4 method for signature 'Pool,ANY'
dbWriteTable(conn, name, value, ...)

## S4 method for signature 'Pool'
dbCreateTable(conn, name, fields, ..., row.names = NULL, temporary = FALSE)

## S4 method for signature 'Pool'
dbAppendTable(conn, name, value, ..., row.names = NULL)

## S4 method for signature 'Pool,ANY'
dbExistsTable(conn, name, ...)

## S4 method for signature 'Pool,ANY'
dbRemoveTable(conn, name, ...)

## S4 method for signature 'Pool'
dbIsReadOnly(dbObj, ...)

## S4 method for signature 'Pool'
sqlData(con, value, row.names = NA, ...)

## S4 method for signature 'Pool'
sqlCreateTable(con, table, fields, row.names = NA, temporary = FALSE, ...)

## S4 method for signature 'Pool'
sqlAppendTable(con, table, values, row.names = NA, ...)

## S4 method for signature 'Pool'
sqlInterpolate(conn, sql, ..., .dots = list())

## S4 method for signature 'Pool'
sqlParseVariables(conn, sql, ...)

## S4 method for signature 'Pool,ANY'
dbQuoteIdentifier(conn, x, ...)

## S4 method for signature 'Pool'
dbUnquoteIdentifier(conn, x, ...)

## S4 method for signature 'Pool'
dbQuoteLiteral(conn, x, ...)

## S4 method for signature 'Pool,ANY'
dbQuoteString(conn, x, ...)

## S4 method for signature 'Pool'
dbAppendTableArrow(conn, name, value, ...)

## S4 method for signature 'Pool'
dbCreateTableArrow(conn, name, value, ..., temporary = FALSE)

## S4 method for signature 'Pool'
dbGetQueryArrow(conn, statement, ...)

## S4 method for signature 'Pool'
dbReadTableArrow(conn, name, ...)

## S4 method for signature 'Pool'
dbSendQueryArrow(conn, statement, ...)

## S4 method for signature 'Pool'
dbWriteTableArrow(conn, name, value, ...)

Arguments

• dbObj: A DBI Driver][DBI::DBIDriver-class] or DBI Connection .

• obj: An R object whose SQL type we want to determine.

• ...: Other arguments passed on to methods.

• conn: A DBI Connection .

• statement: a character string containing SQL.

• name: 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"')

• 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.

• value: A data.frame (or coercible to data.frame).

• fields: Either a character vector or a data frame.

  A named character vector: Names are column names, values are types. Names are escaped with dbQuoteIdentifier(). Field types are unescaped.

  A data frame: field types are generated using dbDataType().

• row.names: Must be NULL.

• temporary: If TRUE, will generate a temporary table.

• con: A database connection.

• table: 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"')

• values: A data frame. Factors will be converted to character vectors. Character vectors will be escaped with dbQuoteString().

• sql: A SQL string containing variables to interpolate. Variables must start with a question mark and can be any valid R identifier, i.e. it must start with a letter or ., and be followed by a letter, digit, . or _.

• .dots: A list of named arguments to interpolate.

• x: A character vector, SQL or Id object to quote as identifier.

Examples

mtcars1 <- mtcars[ c(1:16), ] # first half of the mtcars dataset
mtcars2 <- mtcars[-c(1:16), ] # second half of the mtcars dataset

pool <- dbPool(RSQLite::SQLite())

# write the mtcars1 table into the database
dbWriteTable(pool, "mtcars", mtcars1, row.names = TRUE)

# list the current tables in the database
dbListTables(pool)

# read the "mtcars" table from the database (only 16 rows)
dbReadTable(pool, "mtcars")

# append mtcars2 to the "mtcars" table already in the database
dbWriteTable(pool, "mtcars", mtcars2, row.names = TRUE, append = TRUE)

# read the "mtcars" table from the database (all 32 rows)
dbReadTable(pool, "mtcars")

# get the names of the columns in the databases's table
dbListFields(pool, "mtcars")

# use dbExecute to change the "mpg" and "cyl" values of the 1st row
dbExecute(pool,
  paste(
    "UPDATE mtcars",
    "SET mpg = '22.0', cyl = '10'",
    "WHERE row_names = 'Mazda RX4'"
  )
)

# read the 1st row of "mtcars" table to confirm the previous change
dbGetQuery(pool, "SELECT * FROM mtcars WHERE row_names = 'Mazda RX4'")

# drop the "mtcars" table from the database
dbRemoveTable(pool, "mtcars")

# list the current tables in the database
dbListTables(pool)

poolClose(pool)