query {RMariaDB}

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'
dbBind(res, params, ...)

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

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

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

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

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

Arguments

res

A MariaDBResult object.

params

A list of query parameters to be substituted into a parameterised query.

...

Unused. Needed for compatibility with generic.

n

Number of rows to retrieve. Use -1 to retrieve all rows.

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

A 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.

immediate

If TRUE, uses the mysql_real_query() API instead of mysql_stmt_init(). This allows passing multiple statements (with CLIENT_MULTI_STATEMENTS) and turns off the ability to pass parameters.

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)
}