Getting user provided data out of a database and into R [closed] - r

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I am creating the function below. The purpose is to take in a user provided variable list from an Access database for use in other functions. I would like users to provide a list separated by commas. I have tried several different methods to loop through the provided variable list but cannot get it to operate correctly. My for loop is problematic.
f.extractVariables<-
structure(function
(dbPath,dbName,table,variables
){
# LOAD LIBRARIES
require(RODBC)
require(xlsx)
setwd(dbPath)
db <- odbcConnectAccess2007(dbName)
for (i in 0:length(variables))
{
dataCollection <- sqlQuery(db, 'SELECT table.variables[[i]]
FROM table;')
}
odbcClose(db)
)
}, ex=function(){
#Positive Test to retrieve specified variables from specified location
dbPath = 'z:/sites/'
dbName = 'oysterSites.accdb'
table = 'tblDataSiteOysterSamplingPlan'
variables= (nwLon, nwLat, neLon, neLat)

Answer 1

No need to use a loop here. You can build your query using paste:
variables= "nwLon, nwLat, neLon, neLat" ## user input string
If use give a list a variables:
variables= c("nwLon", "nwLat", "neLon", "neLat")
variables = paste(variables,collapse=",")
Then you build the query as :
query <- paste(paste("SELECT" ,variables),
"FROM table",sep='\n')
cat(query)
# SELECT nwLon, nwLat, neLon, neLat
# FROM table