RMariaDB: query – R documentation

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query

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. For data manipulation queries (i.e. queries that do not return data, such as UPDATE, DELETE, etc.), dbSendStatement() serves as a counterpart to dbSendQuery(), while dbExecute() corresponds to dbGetQuery().

Usage

## S4 method for signature 'MariaDBResult'
dbFetch(res, n = -1, ..., row.names = FALSE)

## S4 method for signature 'MariaDBConnection,character'
dbSendQuery(conn, statement, params = NULL, ...)

## S4 method for signature 'MariaDBConnection,character'
dbSendStatement(conn, statement, params = NULL, ...)

## S4 method for signature 'MariaDBResult'
dbBind(res, params, ...)

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

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

Arguments

`res`	A MariaDBResult object.
`n`	Number of rows to retrieve. Use -1 to retrieve all rows.
`...`	Unused. Needed for compatibility with generic.
`row.names`	Either `TRUE`, `FALSE`, `NA` or a string. If `TRUE`, always translate row names to a column called "row_names". If `FALSE`, never translate row names. If `NA`, translate rownames only if they're a character vector. A string is equivalent to `TRUE`, but allows you to override the default name. For backward compatibility, `NULL` is equivalent to `FALSE`.
`conn`	an MariaDBConnection object.
`statement`	a character vector of length one specifying the SQL statement that should be executed. Only a single SQL statement should be provided.
`params`	A list of query parameters to be substituted into a parameterised query.

Examples

if (mariadbHasDefault()) {
con <- dbConnect(RMariaDB::MariaDB(), dbname = "test")
dbWriteTable(con, "arrests", datasets::USArrests, temporary = 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)

dbClearResult(res)
dbDisconnect(con)
}

RMariaDB

Database Interface and 'MariaDB' Driver

v1.1.1

GPL-3

Authors

Kirill Müller [aut, cre] (<https://orcid.org/0000-0002-1416-3412>), Jeroen Ooms [aut] (<https://orcid.org/0000-0002-4035-0289>), David James [aut], Saikat DebRoy [aut], Hadley Wickham [aut], Jeffrey Horner [aut], R Consortium [fnd], RStudio [cph]

Initial release