We defined users with the names user1, user2, ..., user12 both on the linux server and on the mysql database server running on that machine.
We refer to those usernames as userx, all passwords are "thebigrbook" (without the quotes)

Use the mysql database directly:
1) open a web-browser and go to https://70.34.250.45:4200/ and login as userx with password thebigrbook

notes: 1. note the httpS
       2. if the connection is refused, click [advanced] then [allow] (or proceed to ...)

2) now start mysql with
mysql -u userx -p
and type the password thebigrbook


# ---------------------------------------------------------------------


 # +----------------------------------------------------------------------------+
 # |                               the R code for the                           |
 # |                                   Big R-book                               |
 # |                           by Philippe J.S. De Brouwer                      |
 # +----------------------------------------------------------------------------+
 # | Copyright: (C) Philippe De Brouwer, 2020                                   |
 # |            Owners of the book can use this code for private and commercial |
 # |            use, except re-publishing.                                      |
 # +----------------------------------------------------------------------------+
 # | This document is a true copy of all the R code that appears in the book.   |
 # | It is provided for you so that when you work with the book, you can copy   | 
 # | and paste any code segment that you want to test without typing everything |
 # | again.                                                                     |
 # | No warranties or promises are given.                                       |
 # | Have an intersting time and learn faster than me!                          |
 # | Philippe J.S. De Brouwer                                                   |
 # +----------------------------------------------------------------------------+
 # | For your convenience, blocks are separated by: '# ----------------------'. |
 # +----------------------------------------------------------------------------+
 #
 
 
# ---------------------------------------------------------------------



# install.packages('RMySQL')
library(RMySQL)
# connect to the library
con <- dbConnect(MySQL(), 
                 user     = "user3", 
                 password = "thebigrbook", 
                 dbname   = "library", 
                 host     = "70.34.251.205",
                 port     = 3306
                 )
                 
# in case we would forget to disconnect:
on.exit(dbDisconnect(con))
# ---------------------------------------------------------------------


# Show some information:

show(con)
summary(con, verbose = TRUE)  
# dbGetInfo(con)  # similar as above but in list format
dbListResults(con)
dbListTables(con) # check: this might generate too much output

# Get data:
df_books <- dbGetQuery(con, "SELECT author, COUNT(*) AS nbrBooks 
                     FROM tbl_author_book GROUP BY author;")

# Now, df_books is a data frame that can be used as usual.

# close the connection:
dbDisconnect(con)
# ---------------------------------------------------------------------


# Load the package: 
library(RMySQL)

# db_get_data
# Get data from a MySQL database
# Arguments:
#    con_info -- MySQLConnection object -- the connection info to 
#                                          the MySQL database
#    sSQL     -- character string       -- the SQL statement that 
#                                          selects the records
# Returns
#    data.frame, containing the selected records
db_get_data <- function(con_info, sSQL){
  con <- dbConnect(MySQL(), 
                 user     = con_info$user, 
                 password = con_info$password, 
                 dbname   = con_info$dbname, 
                 host     = con_info$host,
                 port     = con_info$port
                 )
  df <- dbGetQuery(con, sSQL)
  dbDisconnect(con)
  df
}
# ---------------------------------------------------------------------


# db_run_sql
# Run a query that returns no data in an MySQL database
# Arguments:
#    con_info -- MySQLConnection object -- open connection
#    sSQL     -- character string       -- the SQL statement to run
db_run_sql <-function(con_info, sSQL)
{
  con <- dbConnect(MySQL(), 
                 user     = con_info$user, 
                 password = con_info$password, 
                 dbname   = con_info$dbname, 
                 host     = con_info$host
                 )
  rs <- dbSendQuery(con,sSQL)
  dbDisconnect(con)
}
# ---------------------------------------------------------------------


# use the wrapper functions to get data.

# step 1: define the connection info
my_con_info <- list()
my_con_info$user     <- "user5"
my_con_info$password <- "thebigrbook"
my_con_info$dbname   <- "library"
my_con_info$host     <- "70.34.251.205"
my_con_info$port     <- 3306


# step 2: get the data
my_query <- "SELECT COUNT(*) AS nbrBooks 
                     FROM tbl_author_book GROUP BY author;"
df <- db_get_data(my_con_info, my_query)

# step 3: use this data to produce the histogram:
hist(df$nbrBooks, col='khaki3')
# ---------------------------------------------------------------------