query: Execute a SQL statement on a database connection.

In RMySQL: Database Interface and 'MySQL' Driver for R

Execute a SQL statement on a database connection.

Description

To retrieve results a chunk at a time, use dbSendQuery, dbFetch, then dbClearResult. Alternatively, if you want all the results (and they'll fit in memory) use dbGetQuery which sends, fetches and clears for you.

Usage

## S4 method for signature 'MySQLResult,numeric'
dbFetch(res, n = -1, ...)

## S4 method for signature 'MySQLResult,numeric'
fetch(res, n = -1, ...)

## S4 method for signature 'MySQLResult,missing'
dbFetch(res, n = -1, ...)

## S4 method for signature 'MySQLResult,missing'
fetch(res, n = -1, ...)

## S4 method for signature 'MySQLConnection,character'
dbSendQuery(conn, statement, ...)

## S4 method for signature 'MySQLResult'
dbClearResult(res, ...)

## S4 method for signature 'MySQLResult'
dbGetInfo(dbObj, what = "", ...)

## S4 method for signature 'MySQLResult'
dbGetStatement(res, ...)

## S4 method for signature 'MySQLResult,missing'
dbListFields(conn, name, ...)

Arguments

res, dbObj	A MySQLResult object.
n	maximum number of records to retrieve per fetch. Use -1 to retrieve all pending records; use 0 for to fetch the default number of rows as defined in MySQL
...	Unused. Needed for compatibility with generic.
conn	an MySQLConnection object.
statement	a character vector of length one specifying the SQL statement that should be executed. Only a single SQL statment should be provided.
what	optional
name	Table name.

Details

fetch() will be deprecated in the near future; please use dbFetch() instead.

Examples

if (mysqlHasDefault()) {
con <- dbConnect(RMySQL::MySQL(), dbname = "test")
dbWriteTable(con, "arrests", datasets::USArrests, overwrite = TRUE)

# Run query to get results as dataframe
dbGetQuery(con, "SELECT * FROM arrests limit 3")

# Send query to pull requests in batches
res <- dbSendQuery(con, "SELECT * FROM arrests")
data <- dbFetch(res, n = 2)
data
dbHasCompleted(res)

dbListResults(con)
dbClearResult(res)
dbRemoveTable(con, "arrests")
dbDisconnect(con)
}

RMySQL documentation built on Sept. 11, 2024, 6:11 p.m.