如何选择dplyr / sql中的所有列？ [英] How to select all columns in dplyr/sql?

问题描述

我正在将MySQL数据库与 dplyr 连接，并使用 dplyr 和<$ c $处理数据c>％&％;％随后操作。

I am connecting a MySQL data base with dplyr and handle the data with dplyr and the %>% operatot subsequently.

conDplyr <- src_mysql(user = db_user, password = db_pw, dbname = db_name, host = db_host, port = some_port)

dat <- conDplyr %>%
 tbl('table_name') %>%
 select(c1, c2, c3, c4) %>%
 filter(!is.null(c4))

现在，我遍历了一个用例，其中需要选择所有列（整个表）。我发现的所有教程（大约 dplyr ）都是通过选择整个数据框（我没有的）来解决的。

Now, I ran over a use case, in which I need to select all columns (whole table). All tutorials I found (about dplyr) handled this by selecting the whole dataframe (which I do not have)

some_dataframe <- ...
select(some_dataframe)

我没有发现与数据库结合使用的任何建议。也许这一天太长了。有人能帮我吗？

I have not found any suggestions in combination with databases. Perhaps the day was too long. Does anybody could help me please?

最佳抢劫

conDplyr <- src_mysql(...)
dat <- conDplyr %>%
tbl('table_name') %>%
select(everything()) %>%
filter(!is.null(ean))

正常工作。谢谢！如果我没有选择，查询将导致错误（选择未定义的列）。
再一次，我不仅要使用一个已经存在的数据框，而且要使用从数据库查询的表，这就是为什么我必须这样做，如果我错了，请更正我，选择一个。

works just fine. Thanks! If I leave out the select the query results in an error (non-defined columns selected). Again, I did not just want to work with a already existing data frame, but with a table queried from a database, that`s why I am have to do, correct me if I am wrong, an select.

推荐答案

正如@AntoniosK指出的，我不知道您为什么要这样做。但是，您是否尝试过一切？：

As @AntoniosK pointed out I do not know why you would like to do that. However, have you tried everything?:

some_dataframe <- ...
select(everything())

例如：

select(iris, everything()) # or
iris %>% select(everything())

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