rdbirmysql

Error passing a parameter to SQL with RMySQL


I have been trying to find the reason of the error in this code, but I have not been successful. I would like to pass a variable to SQL, but it keeps on giving the same error.

A MWE is the following (just change user and password for the connection).

library(DBI)
library(RMySQL)
library(tidyverse)

data("mtcars")
head(mtcars)

mtcars <- mtcars |>
    rownames_to_column("type") |>
    as_tibble()

# Open a connection to MySQL
conn <- dbConnect(MySQL(), user = "myuser", password = "mypassword")

# Create the appropriate database
dbGetQuery(conn, "CREATE DATABASE mtcars;")
dbGetQuery(conn, "USE mtcars")

# Query that doesn't work:
dbGetQuery(conn, 
           "SELECT COUNT(*) FROM mtcars WHERE cyl = ? ", 
           params = list(8))

This is the error that I keep on getting.

Error in .local(conn, statement, ...) : 
  unused argument (params = list(8))

I have seen in a post ideas like using \ or \\ to escape ? but it didn't work. I have tried to search for similar errors, but I haven't find anything remotely similar.

Thank you for any advice you can give me.


Solution

  • RMySQL does not support params=, and the author (on its github repo) says:

    NOTE: this package is being phased out in favor of the new RMariaDB package.

    Up front, your query should work just fine using the new package. However, I found that loading both RMySQL and RMariaDB breaks things.

    Docker image setup (since I don't have mysql running anywhere):

    docker run --name some-mysql -p 3306:3306 -e MYSQL_ROOT_PASSWORD=my-secret-pw -d mysql:8
    

    In R:

    mysql <- DBI::dbConnect(RMySQL::MySQL(), user="root", password="my-secret-pw", host="127.0.0.1")
    DBI::dbExecute(mysql, "create database quuxdb")
    # [1] 1
    DBI::dbExecute(mysql, "use quuxdb")
    # [1] 0
    DBI::dbExecute(mysql, "create table quux (AA int, BB int)")
    # [1] 0
    DBI::dbExecute(mysql, "insert into quux (AA,BB) values (1,11), (2,22), (3,33)")
    # [1] 3
    DBI::dbGetQuery(mysql, "select * from quux where AA > 1")
    #   AA BB
    # 1  2 22
    # 2  3 33
    DBI::dbGetQuery(mysql, "select * from quux where AA > ?", params=list(1))
    # Error in .local(conn, statement, ...) : 
    #   unused argument (params = list(1))
    

    After I install RMariaDB in the same running R session, I tried to connect but get

    maria <- DBI::dbConnect(RMariaDB::MariaDB(), host="127.0.0.1", password="my-secret-pw", user="root", database="quuxdb")
    # Error in h(simpleError(msg, call)) : 
    #   error in evaluating the argument 'statement' in selecting a method for function 'dbExecute': no slot of name "Id" for this object of class "MySQLConnection"
    # Error in .local(dbObj, ...) : 
    #   no slot of name "Id" for this object of class "MySQLConnection"
    

    On a whim, I started a new R session and ran that again (no error this time) and then continued:

    maria <- DBI::dbConnect(RMariaDB::MariaDB(), host="127.0.0.1", password="my-secret-pw", user="root", dbname="quuxdb")
    DBI::dbGetQuery(maria, "select * from quux where AA > 1")
    #   AA BB
    # 1  2 22
    # 2  3 33
    DBI::dbGetQuery(maria, "select * from quux where AA > ?", params = list(1))
    #   AA BB
    # 1  2 22
    # 2  3 33
    

    I'm not certain if the Id-error is a bug or just a nuance of having two packages that acknowledge connections to the same type of database. Either way, in a fresh R instance, RMariaDB::MariaDB() works with params= (to the same MySQL database).