Build a blocks_to_rowrecs_q() control table that specifies a pivot (query based, takes name of table).

Some discussion and examples can be found here: https://winvector.github.io/FluidData/FluidData.html.

build_pivot_control_q(
  tableName,
  columnToTakeKeysFrom,
  columnToTakeValuesFrom,
  my_db,
  ...,
  prefix = columnToTakeKeysFrom,
  sep = NULL,
  qualifiers = NULL
)

Arguments

tableName	Name of table to scan for new column names.
columnToTakeKeysFrom	character name of column build new column names from.
columnToTakeValuesFrom	character name of column to get values from.
my_db	db handle
...	not used, force later args to be by name
prefix	column name prefix (only used when sep is not NULL)
sep	separator to build complex column names.
qualifiers	optional named ordered vector of strings carrying additional db hierarchy terms, such as schema.

Value

control table

See also

blocks_to_rowrecs_q, build_pivot_control

Examples

if (requireNamespace("DBI", quietly = TRUE) &&
  requireNamespace("RSQLite", quietly = TRUE)) {
  my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
  d <- data.frame(measType = c("wt", "ht"),
                  measValue = c(150, 6),
                  stringsAsFactors = FALSE)
  rquery::rq_copy_to(my_db,
                    'd',
                    d,
                    overwrite = TRUE,
                    temporary = TRUE)
  build_pivot_control_q('d', 'measType', 'measValue',
                        my_db = my_db,
                        sep = '_') %.>%
     print(.)
  DBI::dbDisconnect(my_db)
}
#>   measType   measValue
#> 1       ht measType_ht
#> 2       wt measType_wt