These are methods for the dplyr select(), rename(), and relocate()
generics. They generate the SELECT clause of the SQL query.
These functions do not support predicate functions, i.e. you can
not use where(is.numeric) to select all numeric variables.
Usage
# S3 method for tbl_lazy
select(.data, ...)
# S3 method for tbl_lazy
rename(.data, ...)
# S3 method for tbl_lazy
rename_with(.data, .fn, .cols = everything(), ...)
# S3 method for tbl_lazy
relocate(.data, ..., .before = NULL, .after = NULL)Arguments
- .data
A lazy data frame backed by a database query.
- ...
<
data-masking> Variables, or functions of variables. Usedesc()to sort a variable in descending order.- .fn
A function used to transform the selected
.cols. Should return a character vector the same length as the input.- .cols
<
tidy-select> Columns to rename; defaults to all columns.- .before, .after
<
tidy-select> Destination of columns selected by.... Supplying neither will move columns to the left-hand side; specifying both is an error.
Examples
library(dplyr, warn.conflicts = FALSE)
db <- memdb_frame(x = 1, y = 2, z = 3)
db %>% select(-y) %>% show_query()
#> <SQL>
#> SELECT `x`, `z`
#> FROM `dbplyr_2HkWPaZg2u`
db %>% relocate(z) %>% show_query()
#> <SQL>
#> SELECT `z`, `x`, `y`
#> FROM `dbplyr_2HkWPaZg2u`
db %>% rename(first = x, last = z) %>% show_query()
#> <SQL>
#> SELECT `x` AS `first`, `y`, `z` AS `last`
#> FROM `dbplyr_2HkWPaZg2u`