query: Execute a SQL statement on a database connection.

Description Usage Arguments Examples

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

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## 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

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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 documentation built on May 7, 2018, 1:03 a.m.