fetch-methods {RMySQL}R Documentation

Fetch records from a previously executed query

Description

This method is a straight-forward implementation of the corresponding generic function.

Details

The RMySQL implementations retrieves only n records, and if n is missing it only returns up to fetch.default.rec as specified in the call to MySQL (500 by default).

Methods

res
an MySQLResult object.
n
maximum number of records to retrieve per fetch. Use n = -1 to retrieve all pending records; use a value of n = 0 for fetching the default number of rows fetch.default.rec defined in the MySQL initialization invocation.
...
currently not used.

References

See the Database Interface definition document DBI.pdf in the base directory of this package or http://stat.bell-labs.com/RS-DBI.

See Also

MySQL, dbConnect, dbSendQuery, dbGetQuery, dbClearResult, dbCommit, dbGetInfo, dbReadTable.

Examples

## Not run: 
drv <- dbDriver("MySQL")
con <- dbConnect(drv, user = "opto", password="pure-light", 
                 host = "localhost", dbname="lasers")
res <- dbSendQuery(con, statement = paste(
                      "SELECT w.laser_id, w.wavelength, p.cut_off",
                      "FROM WL w, PURGE P", 
                      "WHERE w.laser_id = p.laser_id",
                      "ORDER BY w.laser_id"))
# we now fetch the first 100 records from the resultSet into a data.frame
data1 <- fetch(res, n = 100)   
dim(data1)

dbHasCompleted(res)

# let's get all remaining records
data2 <- fetch(res, n = -1)
## End(Not run)

[Package RMySQL version 0.6-0 Index]