dbFetch

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Fetch records from a previously executed query

Fetch the next n elements (rows) from the result set and return them as a data.frame.

Usage
dbFetch(res, n = -1, ...)
fetch(res, n = -1, ...)
Arguments
res
An object inheriting from DBIResult.
n
maximum number of records to retrieve per fetch. Use n = -1 to retrieve all pending records. Some implementations may recognize other special values.
...
Other arguments passed on to methods.
Details

fetch is provided for compatibility with older DBI clients - for all new code you are strongly encouraged to use dbFetch. The default method for dbFetch calls fetch so that it is compatible with existing code. Implementors are free to provide methods for dbFetch only.

Value

a data.frame with as many rows as records were fetched and as many columns as fields in the result set.

See Also

close the result set with dbClearResult as soon as you finish retrieving the records you want.

Other DBIResult generics: DBIResult-class, SQL, dbBind, dbClearResult, dbColumnInfo, dbGetInfo, dbGetRowCount, dbGetRowsAffected, dbGetStatement, dbHasCompleted, dbIsValid

Aliases
  • dbFetch
  • fetch
Examples
library(DBI) con <- dbConnect(RSQLite::SQLite(), ":memory:") dbWriteTable(con, "mtcars", mtcars) # Fetch all results rs <- dbSendQuery(con, "SELECT * FROM mtcars WHERE cyl = 4") dbFetch(rs) dbClearResult(rs) # Fetch in chunks rs <- dbSendQuery(con, "SELECT * FROM mtcars") while (!dbHasCompleted(rs)) { chunk <- dbFetch(rs, 10) print(nrow(chunk)) } dbClearResult(rs) dbDisconnect(con)
Documentation reproduced from package DBI, version 0.5-1, License: LGPL (>= 2)

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