dbGetQuery-DatabaseConnectorConnection-character-method: Send query, retrieve results and then clear result set

Description Usage Arguments Details Value See Also

Description

Returns the result of a query as a data frame. dbGetQuery() comes with a default implementation (which should work with most backends) that calls dbSendQuery(), then dbFetch(), ensuring that the result is always free-d by dbClearResult().

\Sexpr[results=rd,stage=render]{DBI:::methods_as_rd("dbGetQuery")}

Usage

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## S4 method for signature 'DatabaseConnectorConnection,character'
dbGetQuery(conn,
  statement, ...)

Arguments

conn

A DBIConnection object, as returned by dbConnect().

statement

a character string containing SQL.

...

Other parameters passed on to methods.

Details

This method is for SELECT queries only (incl. other SQL statements that return a SELECT-alike result, e. g. execution of a stored procedure).

To execute a stored procedure that does not return a result set, use dbExecute().

Some backends may support data manipulation statements through this method for compatibility reasons. However, callers are strongly advised to use dbExecute() for data manipulation statements.

Value

dbGetQuery() always returns a data.frame with as many rows as records were fetched and as many columns as fields in the result set, even if the result is a single value or has one or zero rows. An error is raised when issuing a query over a closed or invalid connection, if the syntax of the query is invalid, or if the query is not a non-NA string. If the n argument is not an atomic whole number greater or equal to -1 or Inf, an error is raised, but a subsequent call to dbGetQuery() with proper n argument succeeds.

See Also

For updates: dbSendStatement() and dbExecute().

Other DBIConnection generics: DBIConnection-class, dbAppendTable, dbCreateTable, dbDataType, dbDisconnect, dbExecute, dbExistsTable, dbGetException, dbGetInfo, dbIsReadOnly, dbIsValid, dbListFields, dbListObjects, dbListResults, dbListTables, dbReadTable, dbRemoveTable, dbSendQuery, dbSendStatement, dbWriteTable


OHDSI/DatabaseConnector documentation built on Nov. 16, 2018, 6:20 p.m.