extras/small_examples/rename_join.md

In WinVector/rquery: Relational Query Generator for Data Manipulation at Scale

rename join example

Example of automatic insertion of a rename node on a join.

library("rquery")
library("wrapr")

raw_connection <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
RSQLite::initExtension(raw_connection)
db <- rquery_db_info(
  connection = raw_connection,
  is_dbi = TRUE,
  connection_options = rq_connection_tests(raw_connection))

t1l <- data.frame(a = c(1, 2), b = c(3, 4))
t1r <- rq_copy_to(db, "t1r", t1l)
t2l <- data.frame(c = c(2, 1), d = c(6, 5))
t2r <- rq_copy_to(db, "t2r", t2l)

ops <- natural_join(t1r, t2r, by = c("a" = "c"))

cat(format(ops))

## table(`t1r`; 
##   a,
##   b) %.>%
##  natural_join(.,
##   table(`t2r`; 
##     c,
##     d) %.>%
##    rename(.,
##     c('a' = 'c')),
##   j= INNER, by= a)

# cat(to_sql(ops, db))

execute(db, ops) %.>%
  knitr::kable(.)

| a | b | d | | -: | -: | -: | | 1 | 3 | 5 | | 2 | 4 | 6 |

DBI::dbDisconnect(raw_connection)

library("rqdatatable")

natural_join(t1l, t2l, by = c("a" = "c"))

##    a b d
## 1: 1 3 5
## 2: 2 4 6

ex_data_table(ops,
              tables = list("t1r" = t1l, "t2r" = t2l)) %.>%
  knitr::kable(.)

| a | b | d | | -: | -: | -: | | 1 | 3 | 5 | | 2 | 4 | 6 |

list("t1r" = t1l, "t2r" = t2l) %.>% 
  ops %.>%
  knitr::kable(.)

| a | b | d | | -: | -: | -: | | 1 | 3 | 5 | | 2 | 4 | 6 |

WinVector/rquery documentation built on Aug. 24, 2023, 11:12 a.m.