How to pass function parameters in sql query in R? [duplicate] - sql

Question

This question already has answers here:
Pass R variable to RODBC's sqlQuery? [duplicate]
(4 answers)
Closed 5 years ago.
I have the following function in R:
dbhandle <- odbcDriverConnect('driver={SQL Server};
server=myServer;database=myDB;
trusted_connection=true')
func <- function(x){
sqlQuery(dbhandle, 'select attr from myTable where cond = x')
}
I want to know how to pass the x parameter to the where condition for the cond attribute. For example, I want to calculate func(10), then the query must be:
select attr from myTable where cond = 10

Answer 1

when using RODBC, I prefer to use parameterized queries. This becomes more valuable when you are passing character strings, as this avoids SQL Injection.
library(RODBCext)
sqlExecute(dbhandle,
"select attr from myTable where cond = ?",
data = list(cond = 10),
fetch = TRUE,
stringsAsFactors = FALSE)

Answer 2

You could try with paste:
func <- function(x){
sqlQuery(dbhandle, paste('select attr from myTable where cond =', x))
}

Answer 3

I like the glue package for these things, though it's really the same as paste, just prettier :
library(glue)
func <- function(x){
sqlQuery(dbhandle, glue('select attr from myTable where cond = {x}'))
}

Answer 4

In this simple case you could even use dplyr itself:
library(dplyr)
func <- function(x) {
tbl(dbhandle, "myTable") %>%
select(attr) %>%
filter(cond == x) %>%
collect()
}