Sum in JDBC

Java Libraries

Copy JAR files which are listed below:

mysql-connector-java-5.1.36.jar

Create Database

Create a database with the name is advancedjava. This database have 1 tables: Product table.

--
-- Table structure for table `product`
--

CREATE TABLE `product` (
  `id` int(11) NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `name` varchar(250) COLLATE utf8_unicode_ci NOT NULL,
  `price` decimal(10,1) NOT NULL,
  `quantity` int(11) NOT NULL,
  `description` text COLLATE utf8_unicode_ci NOT NULL,
  `featured` tinyint(1) NOT NULL,
  `dateCreated` date NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Dumping data for table `product`
--

INSERT INTO `product` (`name`, `price`, `quantity`, `description`, `featured`, `dateCreated`) VALUES
('laptop 1', '2.0', 5, 'Description of laptop 1', 1, '2018-03-19'),
('laptop 2', '12.0', 7, 'Description of laptop 2', 0, '2018-03-21'),
('computer 1', '4.0', 6, 'Description of computer 1', 1, '2018-03-23'),
('computer 2', '10.0', 6, 'Description of computer 2', 1, '2018-03-14'),
('computer 3', '21.0', 4, 'Description of computer 3', 0, '2018-03-26'),
('tivi 1', '17.0', 2, 'Description of tivi 1', 1, '2018-03-23'),
('tivi 2', '32.0', 8, 'Description of tivi 2', 0, '2018-03-29');

Structure of Product Table

Data of Product Table

Create ConnectDatabase Class

Create new package named models. In this package, create new java class named ConnectDatabase.java as below:

package models;

import java.sql.Connection;
import java.sql.DriverManager;

public class ConnectDatabase {

	public static Connection getConnection() {
		Connection connection = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/advancedjava", "root", "123456");
		} catch (Exception e) {
			connection = null;
		}
		return connection;
	}

}

Create ProductModel Class

In models package, create new java class named ProductModel.java contains methods to interact with the database.

package models;

import java.math.BigDecimal;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class ProductModel {

	public int sumQuantities() {
		int result = 0;
		try {
			PreparedStatement preparedStatement = ConnectDatabase.getConnection().prepareStatement("select sum(quantity) from product");
			ResultSet resultSet = preparedStatement.executeQuery();
			resultSet.next();
			result = resultSet.getInt(1);
		} catch (Exception e) {
			result = 0;
		}
		return result;
	}

	public BigDecimal total() {
		BigDecimal result = null;
		try {
			PreparedStatement preparedStatement = ConnectDatabase.getConnection().prepareStatement("select sum(price * quantity) from product");
			ResultSet resultSet = preparedStatement.executeQuery();
			resultSet.next();
			result = resultSet.getBigDecimal(1);
		} catch (Exception e) {
			result = null;
		}
		return result;
	}

}

Structure of Project

Run Application

Create new package named demo. In this package, create new java class named Main.java as below:

package demo;

import models.ProductModel;

public class Main {

	public static void main(String[] args) {

		ProductModel productModel = new ProductModel();
		System.out.println("Sum Quantities: " + productModel.sumQuantities());
		System.out.println("Total: " + productModel.total());

	}

}

Output

Sum Quantities: 38
Total: 552.0