Writes, overwrites or appends a data frame to a database table, optionally converting row names to a column and specifying SQL data types for fields.
DBI:::methods_as_rd("dbWriteTable")
dbWriteTable(conn, name, value, ...)
dbWriteTable()
returns TRUE
, invisibly.
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"')
A data.frame (or coercible to data.frame).
Other parameters passed on to methods.
If the table exists, and both append
and overwrite
arguments are unset,
or append = TRUE
and the data frame with the new data has different
column names,
an error is raised; the remote table remains unchanged.
An error is raised when calling this method for a closed
or invalid connection.
An error is also raised
if name
cannot be processed with dbQuoteIdentifier()
or
if this results in a non-scalar.
Invalid values for the additional arguments row.names
,
overwrite
, append
, field.types
, and temporary
(non-scalars,
unsupported data types,
NA
,
incompatible values,
duplicate
or missing names,
incompatible columns)
also raise an error.
The following arguments are not part of the dbWriteTable()
generic
(to improve compatibility across backends)
but are part of the DBI specification:
row.names
(default: FALSE
)
overwrite
(default: FALSE
)
append
(default: FALSE
)
field.types
(default: NULL
)
temporary
(default: FALSE
)
They must be provided as named arguments. See the "Specification" and "Value" sections 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: dbWriteTable()
will do the quoting,
perhaps by calling dbQuoteIdentifier(conn, x = name)
If the result of a call to dbQuoteIdentifier()
: no more quoting is done
The value
argument must be a data frame
with a subset of the columns of the existing table if append = TRUE
.
The order of the columns does not matter with append = TRUE
.
If the overwrite
argument is TRUE
, an existing table of the same name
will be overwritten.
This argument doesn't change behavior if the table does not exist yet.
If the append
argument is TRUE
, the rows in an existing table are
preserved, and the new data are appended.
If the table doesn't exist yet, it is created.
If the temporary
argument is TRUE
, the table is not available in a
second connection and is gone after reconnecting.
Not all backends support this argument.
A regular, non-temporary table is visible in a second connection,
in a pre-existing connection,
and after reconnecting to the database.
SQL keywords can be used freely in table names, column names, and data. Quotes, commas, spaces, and other special characters such as newlines and tabs, can also be used in the data, and, if the database supports non-syntactic identifiers, also for table names and column names.
The following data types must be supported at least,
and be read identically with dbReadTable()
:
integer
numeric
(the behavior for Inf
and NaN
is not specified)
logical
NA
as NULL
64-bit values (using "bigint"
as field type); the result can be
converted to a numeric, which may lose precision,
converted a character vector, which gives the full decimal representation
written to another table and read again unchanged
character (in both UTF-8 and native encodings), supporting empty strings before and after a non-empty string
factor (returned as character)
list of raw (if supported by the database)
objects of type blob::blob (if supported by the database)
date
(if supported by the database;
returned as Date
),
also for dates prior to 1970 or 1900 or after 2038
time
(if supported by the database;
returned as objects that inherit from difftime
)
timestamp
(if supported by the database;
returned as POSIXct
respecting the time zone but not necessarily preserving the
input time zone),
also for timestamps prior to 1970 or 1900 or after 2038
respecting the time zone but not necessarily preserving the
input time zone)
Mixing column types in the same table is supported.
The field.types
argument must be a named character vector with at most
one entry for each column.
It indicates the SQL data type to be used for a new column.
If a column is missed from field.types
, the type is inferred
from the input data with dbDataType()
.
The interpretation of rownames depends on the row.names
argument,
see sqlRownamesToColumn()
for details:
If FALSE
or NULL
, row names are ignored.
If TRUE
, row names are converted to a column named "row_names",
even if the input data frame only has natural row names from 1 to nrow(...)
.
If NA
, a column named "row_names" is created if the data has custom row names,
no extra column is created in the case of natural row names.
If a string, this specifies the name of the column in the remote table that contains the row names, even if the input data frame only has natural row names.
The default is row.names = FALSE
.
This function expects a data frame.
Use dbWriteTableArrow()
to write an Arrow object.
This function is useful if you want to create and load a table at the same time.
Use dbAppendTable()
or dbAppendTableArrow()
for appending data to an existing
table, dbCreateTable()
or dbCreateTableArrow()
for creating a table,
and dbExistsTable()
and dbRemoveTable()
for overwriting tables.
DBI only standardizes writing data frames with dbWriteTable()
.
Some backends might implement methods that can consume CSV files
or other data formats.
For details, see the documentation for the individual methods.
Other DBIConnection generics:
DBIConnection-class
,
dbAppendTable()
,
dbAppendTableArrow()
,
dbCreateTable()
,
dbCreateTableArrow()
,
dbDataType()
,
dbDisconnect()
,
dbExecute()
,
dbExistsTable()
,
dbGetException()
,
dbGetInfo()
,
dbGetQuery()
,
dbGetQueryArrow()
,
dbIsReadOnly()
,
dbIsValid()
,
dbListFields()
,
dbListObjects()
,
dbListResults()
,
dbListTables()
,
dbQuoteIdentifier()
,
dbReadTable()
,
dbReadTableArrow()
,
dbRemoveTable()
,
dbSendQuery()
,
dbSendQueryArrow()
,
dbSendStatement()
,
dbUnquoteIdentifier()
,
dbWriteTableArrow()
if (FALSE) { # requireNamespace("RSQLite", quietly = TRUE)
con <- dbConnect(RSQLite::SQLite(), ":memory:")
dbWriteTable(con, "mtcars", mtcars[1:5, ])
dbReadTable(con, "mtcars")
dbWriteTable(con, "mtcars", mtcars[6:10, ], append = TRUE)
dbReadTable(con, "mtcars")
dbWriteTable(con, "mtcars", mtcars[1:10, ], overwrite = TRUE)
dbReadTable(con, "mtcars")
# No row names
dbWriteTable(con, "mtcars", mtcars[1:10, ], overwrite = TRUE, row.names = FALSE)
dbReadTable(con, "mtcars")
}
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