Join two tables

A join of a desired type is performed between table_1 and table_2. The two tables need to be directly connected by a foreign key relation. Since this function is a wrapper around dm_flatten_to_tbl(), the LHS of the join will always be a "child table", i.e. a table referencing the other table.

dm_join_to_tbl(dm, table_1, table_2, join = left_join)

Arguments

dm	A dm object.
table_1	One of the tables involved in the join.
table_2	The second table of the join.
join	The type of join to be performed, see dplyr::join().

Value

The resulting table of the join.

See also

Other flattening functions: dm_flatten_to_tbl()

Examples

dm_nycflights13() %>%
  dm_join_to_tbl(airports, flights)
#> # A tibble: 11,227 x 26
#>     year month   day dep_time sched_dep_time dep_delay arr_time sched_arr_time
#>    <int> <int> <int>    <int>          <int>     <dbl>    <int>          <int>
#>  1  2013     1    10        3           2359         4      426            437
#>  2  2013     1    10       16           2359        17      447            444
#>  3  2013     1    10      450            500       -10      634            648
#>  4  2013     1    10      520            525        -5      813            820
#>  5  2013     1    10      530            530         0      824            829
#>  6  2013     1    10      531            540        -9      832            850
#>  7  2013     1    10      535            540        -5     1015           1017
#>  8  2013     1    10      546            600       -14      645            709
#>  9  2013     1    10      549            600       -11      652            724
#> 10  2013     1    10      550            600       -10      649            703
#> # … with 11,217 more rows, and 18 more variables: arr_delay <dbl>,
#> #   carrier <chr>, flight <int>, tailnum <chr>, origin <chr>, dest <chr>,
#> #   air_time <dbl>, distance <dbl>, hour <dbl>, minute <dbl>, time_hour <dttm>,
#> #   name <chr>, lat <dbl>, lon <dbl>, alt <dbl>, tz <dbl>, dst <chr>,
#> #   tzone <chr>

# same result is achieved with:
dm_nycflights13() %>%
  dm_join_to_tbl(flights, airports)
#> # A tibble: 11,227 x 26
#>     year month   day dep_time sched_dep_time dep_delay arr_time sched_arr_time
#>    <int> <int> <int>    <int>          <int>     <dbl>    <int>          <int>
#>  1  2013     1    10        3           2359         4      426            437
#>  2  2013     1    10       16           2359        17      447            444
#>  3  2013     1    10      450            500       -10      634            648
#>  4  2013     1    10      520            525        -5      813            820
#>  5  2013     1    10      530            530         0      824            829
#>  6  2013     1    10      531            540        -9      832            850
#>  7  2013     1    10      535            540        -5     1015           1017
#>  8  2013     1    10      546            600       -14      645            709
#>  9  2013     1    10      549            600       -11      652            724
#> 10  2013     1    10      550            600       -10      649            703
#> # … with 11,217 more rows, and 18 more variables: arr_delay <dbl>,
#> #   carrier <chr>, flight <int>, tailnum <chr>, origin <chr>, dest <chr>,
#> #   air_time <dbl>, distance <dbl>, hour <dbl>, minute <dbl>, time_hour <dttm>,
#> #   name <chr>, lat <dbl>, lon <dbl>, alt <dbl>, tz <dbl>, dst <chr>,
#> #   tzone <chr>

# this gives an error, because the tables are not directly linked to each other:
try(
  dm_nycflights13() %>%
    dm_join_to_tbl(airlines, airports)
)
#> Error : Tables `airlines` and `airports` are not directly linked by a foreign key relation.