R and MySQL Database Tutorial

# Creating a database using RMySQL in R >library(RMySQL) #Load RMySQL packages The function dbConnect create a connection to a DBMS. The function requires : - a character string specifying the name of DBMS driver, e.g., "RSQLite", "RMySQL", "RPostgreSQL", or an existing DBIConnection object. -authorization arguments needed by the DBMS instance; these typically include user, password, dbname, host, etc. >mydb <- dbConnect(MySQL(), user=’io’, password=’1234', host='localhost') # Connect to the local host. The function dbSendQuery only submits and synchronously executes the SQL statement to the database engine. It does not extracts any records >dbSendQuery(mydb, "CREATE DATABASE bookstore;") # Create database bookstore >dbSendQuery(mydb, "USE bookstore” ) # Use database bookstore

# Creating a table in a database using RMySQL . >dbSendQuery(mydb, "drop table if exists books, authors") # Remove table if exist >dbSendQuery(mydb, " CREATE TABLE books ( book_id INT, title VARCHAR(50), author VARCHAR(50));") # creating tables in bookstore: >dbSendQuery(mydb, "ALTER TABLE books CHANGE COLUMN book_id book_id INT AUTO_INCREMENT PRIMARY KEY, CHANGE COLUMN author author_id INT, ADD COLUMN description TEXT, ADD COLUMN genre ENUM('novel','poetry','drama', 'tutorials', 'text', 'other'), ADD COLUMN publisher_id INT, ADD COLUMN pub_year VARCHAR(4), ADD COLUMN isbn VARCHAR(20);") >dbSendQuery(mydb, "CREATE TABLE authors (author_id INT AUTO_INCREMENT PRIMARY KEY, author_last VARCHAR(50), author_first VARCHAR(50), country VARCHAR(50));")

# Adding data into tables >dbSendQuery(mydb, "INSERT INTO authors (author_last, author_first, country) VALUES('Kumar','Manoj','India');") # Fetch data from tables and close connection The function dbFetch records from a previously executed query. >res<-dbSendQuery(mydb, "SELECT LAST_INSERT_ID();") >last_id <-dbFetch (res) The funtion dbClearResult frees all resources (local and remote) associated with a result set. It some cases (e.g., very large result sets) this can be a critical step to avoid exhausting resources (memory, file descriptors, etc.) >dbClearResult (res) The funtion dbDisconnect closes the connection, discards all pending work, and frees resources (e.g., memory, sockets). >dbDisconnect (mydb)