Execute a data manipulation statement on a given database connection
The dbSendStatement() method only submits and synchronously executes the
SQL data manipulation statement (e.g., UPDATE, DELETE,
INSERT INTO, DROP TABLE, ...) to the database engine. To query
the number of affected rows, call dbGetRowsAffected() on the
returned result object. You must also call dbClearResult() after
that. For interactive use, you should almost always prefer
dbExecute().
dbSendStatement(conn, statement, ...)
conn |
A DBIConnection object, as returned by
|
statement |
a character string containing SQL. |
... |
Other parameters passed on to methods. |
dbSendStatement() comes with a default implementation that simply
forwards to dbSendQuery(), to support backends that only
implement the latter.
dbSendStatement() returns
an S4 object that inherits from DBIResult.
The result set can be used with dbGetRowsAffected() to
determine the number of rows affected by the query.
Once you have finished using a result, make sure to clear it
with dbClearResult().
An error is raised when issuing a statement over a closed
or invalid connection,
or if the statement is not a non-NA string.
An error is also raised if the syntax of the query is invalid
and all query parameters are given (by passing the params argument)
or the immediate argument is set to TRUE.
The following arguments are not part of the dbSendStatement() generic
(to improve compatibility across backends)
but are part of the DBI specification:
params (default: NULL)
immediate (default: NULL)
They must be provided as named arguments. See the "Specification" sections for details on their usage.
No warnings occur under normal conditions.
When done, the DBIResult object must be cleared with a call to
dbClearResult().
Failure to clear the result set leads to a warning
when the connection is closed.
If the backend supports only one open result set per connection,
issuing a second query invalidates an already open result set
and raises a warning.
The newly opened result set is valid
and must be cleared with dbClearResult().
The param argument allows passing query parameters, see dbBind() for details.
immediate argumentThe immediate argument supports distinguishing between "direct"
and "prepared" APIs offered by many database drivers.
Passing immediate = TRUE leads to immediate execution of the
query or statement, via the "direct" API (if supported by the driver).
The default NULL means that the backend should choose whatever API
makes the most sense for the database, and (if relevant) tries the
other API if the first attempt fails. A successful second attempt
should result in a message that suggests passing the correct
immediate argument.
Examples for possible behaviors:
DBI backend defaults to immediate = TRUE internally
A query without parameters is passed: query is executed
A query with parameters is passed:
params not given: rejected immediately by the database
because of a syntax error in the query, the backend tries
immediate = FALSE (and gives a message)
params given: query is executed using immediate = FALSE
DBI backend defaults to immediate = FALSE internally
A query without parameters is passed:
simple query: query is executed
"special" query (such as setting a config options): fails,
the backend tries immediate = TRUE (and gives a message)
A query with parameters is passed:
params not given: waiting for parameters via dbBind()
params given: query is executed
For queries: dbSendQuery() and dbGetQuery().
Other DBIConnection generics:
DBIConnection-class,
dbAppendTable(),
dbCreateTable(),
dbDataType(),
dbDisconnect(),
dbExecute(),
dbExistsTable(),
dbGetException(),
dbGetInfo(),
dbGetQuery(),
dbIsReadOnly(),
dbIsValid(),
dbListFields(),
dbListObjects(),
dbListResults(),
dbListTables(),
dbReadTable(),
dbRemoveTable(),
dbSendQuery(),
dbWriteTable()
con <- dbConnect(RSQLite::SQLite(), ":memory:") dbWriteTable(con, "cars", head(cars, 3)) rs <- dbSendStatement( con, "INSERT INTO cars (speed, dist) VALUES (1, 1), (2, 2), (3, 3)" ) dbHasCompleted(rs) dbGetRowsAffected(rs) dbClearResult(rs) dbReadTable(con, "cars") # there are now 6 rows # Pass one set of values directly using the param argument: rs <- dbSendStatement( con, "INSERT INTO cars (speed, dist) VALUES (?, ?)", params = list(4L, 5L) ) dbClearResult(rs) # Pass multiple sets of values using dbBind(): rs <- dbSendStatement( con, "INSERT INTO cars (speed, dist) VALUES (?, ?)" ) dbBind(rs, list(5:6, 6:7)) dbBind(rs, list(7L, 8L)) dbClearResult(rs) dbReadTable(con, "cars") # there are now 10 rows dbDisconnect(con)
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