Tidy or other clever methods to importing .accdb tables into R

Question

I am attempting to import all of the tables within a relational MS Access database (.accdb) into R as separate data.frames. I have previously relied upon dbplyr and RMariaDB when accessing relational SQL databases stored online and I was under initial impressions that I could appropriate some of the methods to this.accdb, but I am becoming persuaded I was mistaken.

I have accomplished what I wanted to do with this code:

#### Libraries =================================================================
library(RODBC)
library(dplyr)
library(dbplyr)

#### Import database ===========================================================
# Define connection strings
dbq_string <- paste0("DBQ=", getwd(),"my_database.accdb")
driver_string <- "Driver={Microsoft Access Driver (*.mdb, *.accdb)};"
db_connect_string <- paste0(driver_string, dbq_string)

# Create .accdb connection
con <- odbcDriverConnect(db_connect_string)

#### Extract tables to data.frames
table1 <- sqlFetch(con, "tbltable1")
table2 <- sqlFetch(con, "tbltable2")
table3 <- sqlFetch(con, "tbltable3")

I am seeking advice on two topics here: 1.) Is there a tidyverse way of going about this? I've previously used code like:

table1 <- tbl(con, "tbltable1")
Table1 <- table1 %>% select(my_col) %>% collect()

is this not possible grammar for working through Access?

2.) Can my code where I am extracting tables to data.frames be refined by an apply-family function? I previously experimented with functions to get all of the table names (table_names) and pass it as an argument to an apply function to assign each table. I was under the impression that something like lapply(table1, sqlFetch, con) would do it, but I receive an error indicating improper table connection.

Answer 1

Based on this answer, you need to use the DBI package to connect to a database in order to then use dbplyr. You may also find this question helpful.

Once you have successfully connected R and Access, then yes I would suggest:

table1 <- tbl(con, "tbltable1")
Table1 <- table1 %>% select(my_col) %>% collect()

As a good tidyverse way of approaching reading all the tables into R.

If you want to do this with lapply , then the key thing is probably to name the extra arguments.

table_names = c("table1", "table2", "table3")

all_tables = lapply(table_names, sqlFetch, channel = con)

Will likely work. But omitting the channel = may fail (because channel is an argument for sqlFetch not for lapply ).

Doing this in a tidyverse way, perhaps something like:

read_tbl = function(con, tbl_name){
  tbl(con, tbl_name) %>% collect()
}

all_tables = lapply(table_names, read_tbl, con = con)