View source: R/select_columns.R
select_columns | R Documentation |
Make a select columns node (not a relational operation).
select_columns(source, columns, env = parent.frame())
source |
source to select from. |
columns |
list of distinct column names. |
env |
environment to look to. |
select columns node.
if (requireNamespace("DBI", quietly = TRUE) && requireNamespace("RSQLite", quietly = TRUE)) {
my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
d <- rq_copy_to(my_db, 'd',
data.frame(AUC = 0.6, R2 = 0.2))
optree <- select_columns(d, 'AUC')
cat(format(optree))
sql <- to_sql(optree, my_db)
cat(sql)
print(DBI::dbGetQuery(my_db, sql))
DBI::dbDisconnect(my_db)
}
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