dm_add_pk {dm}

Add a primary key

Description

dm_add_pk() marks the specified columns as the primary key of the specified table. If check == TRUE, then it will first check if the given combination of columns is a unique key of the table. If force == TRUE, the function will replace an already set key, without altering foreign keys previously pointing to that primary key.

Usage

dm_add_pk(
  dm,
  table,
  columns,
  ...,
  autoincrement = FALSE,
  check = FALSE,
  force = FALSE
)

Arguments

dm

A dm object.

table

A table in the dm.

columns

Table columns, unquoted. To define a compound key, use c(col1, col2).

...

These dots are for future extensions and must be empty.

autoincrement

If TRUE, the column specified in columns will be populated automatically with a sequence of integers.

check

Boolean, if TRUE, a check is made if the combination of columns is a unique key of the table.

force

Boolean, if FALSE (default), an error will be thrown if there is already a primary key set for this table. If TRUE, a potential old pk is deleted before setting a new one.

Details

There can be only one primary key per table in a dm. It's possible though to set an unlimited number of unique keys using dm_add_uk() or adding foreign keys pointing to columns other than the primary key columns with dm_add_fk().

Value

An updated dm with an additional primary key.

See Also

Other primary key functions: dm_add_uk(), dm_get_all_pks(), dm_get_all_uks(), dm_has_pk(), dm_rm_pk(), dm_rm_uk(), enum_pk_candidates()

Examples

nycflights_dm <- dm(
  planes = nycflights13::planes,
  airports = nycflights13::airports,
  weather = nycflights13::weather
)

nycflights_dm %>%
  dm_draw()

# Create primary keys:
nycflights_dm %>%
  dm_add_pk(planes, tailnum) %>%
  dm_add_pk(airports, faa, check = TRUE) %>%
  dm_add_pk(weather, c(origin, time_hour)) %>%
  dm_draw()

# Keys can be checked during creation:
try(
  nycflights_dm %>%
    dm_add_pk(planes, manufacturer, check = TRUE)
)