rquery (version 1.4.99)

columns_used: Return columns used

Description

Return columns used

Usage

columns_used(x, ..., using = NULL)

Value

vector of table qualified column names.

Arguments

x

rquery operation tree.

...

generic additional arguments (not used)

using

character, if not NULL set of columns used from above.

Examples

if (requireNamespace("DBI", quietly = TRUE) && requireNamespace("RSQLite", quietly = TRUE)) {
  my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
  d1 <- rq_copy_to(my_db, 'd1',
                    data.frame(AUC = 0.6, R2 = 0.2))
  d2 <- rq_copy_to(my_db, 'd2',
                    data.frame(AUC = 0.6, D = 0.3))
  optree <- natural_join(d1, d2, by = "AUC")
  cat(format(optree))
  print(columns_used(optree))
  DBI::dbDisconnect(my_db)
}