R MySQL – Delete Data

Introduction

Deleting data from a MySQL database from R allows you to remove specific records based on certain conditions. The RMySQL package provides functions to connect to MySQL databases and execute SQL queries, making it easy to delete data directly from R.

Installing and Loading the RMySQL Package

First, you need to install and load the RMySQL package. You can install it from CRAN using the install.packages() function.

Installing the Package

# Install the RMySQL package
install.packages("RMySQL")

Loading the Package

# Load the RMySQL package
library(RMySQL)

Establishing a Connection

To establish a connection to a MySQL database, you need the following information:

• Hostname or IP address of the MySQL server
• Username
• Password
• Database name

Example: Establishing a Connection

Example:

# Establishing a connection to the MySQL database
conn <- dbConnect(RMySQL::MySQL(),
                  dbname = "your_database_name",
                  host = "your_host_name",
                  port = 3306,  # Default MySQL port
                  user = "your_username",
                  password = "your_password")

# Check if the connection is successful
print(conn)

Creating a Table and Inserting Data

For demonstration purposes, let’s create a table and insert some sample data. You can skip this step if you already have a table with data in your MySQL database.

Example: Creating a Table and Inserting Data

Example:

# SQL query to create a table
create_table_query <- "
CREATE TABLE IF NOT EXISTS employees (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(100) NOT NULL,
  age INT NOT NULL,
  gender CHAR(1) NOT NULL,
  salary DECIMAL(10, 2) NOT NULL
);
"

# Executing the query to create the table
dbSendQuery(conn, create_table_query)
print("Table 'employees' created successfully")

# SQL query to insert data into the table
insert_data_query <- "
INSERT INTO employees (name, age, gender, salary) VALUES
('Alice', 30, 'F', 50000.00),
('Bob', 25, 'M', 45000.00),
('Charlie', 35, 'M', 55000.00),
('Diana', 28, 'F', 48000.00),
('Eve', 40, 'F', 60000.00);
"

# Executing the query to insert data
dbSendQuery(conn, insert_data_query)
print("Data inserted into 'employees' table successfully")

Deleting Data

You can delete data from a MySQL table using the dbSendQuery() function to execute an SQL DELETE statement.

Example: Deleting Data

Example:

# SQL query to delete data
delete_query <- "DELETE FROM employees WHERE name = 'Bob';"

# Executing the query to delete data
dbSendQuery(conn, delete_query)
print("Data deleted from 'employees' table successfully")

Example Program Using MySQL Connection to Delete Data

Here is an example program that demonstrates the complete process of connecting to a MySQL database, creating a table, inserting data, deleting data, and closing the connection.

Example Program

# R Program to Demonstrate Deleting Data from MySQL Database

# Install and load the necessary package
install.packages("RMySQL")
library(RMySQL)

# Establishing a connection to the MySQL database
conn <- dbConnect(RMySQL::MySQL(),
                  dbname = "your_database_name",
                  host = "your_host_name",
                  port = 3306,  # Default MySQL port
                  user = "your_username",
                  password = "your_password")

# Check if the connection is successful
print("Connection established:")
print(conn)

# SQL query to create a table
create_table_query <- "
CREATE TABLE IF NOT EXISTS employees (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(100) NOT NULL,
  age INT NOT NULL,
  gender CHAR(1) NOT NULL,
  salary DECIMAL(10, 2) NOT NULL
);
"

# Executing the query to create the table
dbSendQuery(conn, create_table_query)
print("Table 'employees' created successfully")

# SQL query to insert data into the table
insert_data_query <- "
INSERT INTO employees (name, age, gender, salary) VALUES
('Alice', 30, 'F', 50000.00),
('Bob', 25, 'M', 45000.00),
('Charlie', 35, 'M', 55000.00),
('Diana', 28, 'F', 48000.00),
('Eve', 40, 'F', 60000.00);
"

# Executing the query to insert data
dbSendQuery(conn, insert_data_query)
print("Data inserted into 'employees' table successfully")

# SQL query to delete data
delete_query <- "DELETE FROM employees WHERE name = 'Bob';"

# Executing the query to delete data
dbSendQuery(conn, delete_query)
print("Data deleted from 'employees' table successfully")

# Closing the connection
dbDisconnect(conn)
print("Connection closed")

Conclusion

In this chapter, you learned how to delete data from a MySQL database from R using the RMySQL package. You also learned how to create a table, insert data, and close the database connection. By mastering these functions, you can efficiently manage and manipulate data in MySQL databases within your R programs.