R用户定义的函数，用于通过ODBC导入ACCESS表

Question

this might be something simple, but I couldn't figure out a viable solution.

My setup is:

    R version 3.3.1 (2016-06-21)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows >= 8 x64 (build 9200)

locale:
[1] LC_COLLATE=Portuguese_Brazil.1252  LC_CTYPE=Portuguese_Brazil.1252    LC_MONETARY=Portuguese_Brazil.1252 LC_NUMERIC=C                      
[5] LC_TIME=Portuguese_Brazil.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
[1] tools_3.3.1  rpart_4.1-10

I'm building a function to import files from ACCESS DB via ODBC as folow:

importa.sql <- function(someFile)
  {
    library(RODBC) 
    con <- odbcConnect("someTable") 
    qry<-paste("(","SELECT * FROM ",someFile,")")
    someFile <- sqlQuery(con,qry,stringsAsFactors=FALSE) 
  }

I've tested each line and the code is working as expected. The problem is: when I run the function, it seems to work perfectly, but there's no file imported!!!

Does anyone could help me?

Answer 1

Your function return NULL because the last statement of the function ir assignment to the local object someFile . It would be good to close the connection. Try this function.

importa.sql <- function(someFile) {
  library(RODBC) 
  con <- odbcConnect("someTable") 
  qry <- paste("(", "SELECT * FROM ", someFile, ")")
  df <- sqlQuery(con, qry, stringsAsFactors = FALSE)
  close(con)
  return(df)
}

Answer 2

In case of someone has the same doubt, the solution is really really simple.

Just call the function this way:

file <- importa.sql(someFile)