Group By Clause 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,
  `manufacturer` varchar(20)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

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

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

Structure of Product Table

Data of Product Table

Entities Class

Create new package named entities. In this package, create new java class named Group.java as below:

Group Entity

package entities;

import java.math.BigDecimal;

public class Group implements java.io.Serializable {

	private String manufacturer;
	private BigDecimal minPrice;
	private BigDecimal maxPrice;
	private int sumQuantities;
	private int countProduct;
	private double avgPrice;

	public String getManufacturer() {
		return manufacturer;
	}

	public void setManufacturer(String manufacturer) {
		this.manufacturer = manufacturer;
	}

	public BigDecimal getMinPrice() {
		return minPrice;
	}

	public void setMinPrice(BigDecimal minPrice) {
		this.minPrice = minPrice;
	}

	public BigDecimal getMaxPrice() {
		return maxPrice;
	}

	public void setMaxPrice(BigDecimal maxPrice) {
		this.maxPrice = maxPrice;
	}

	public int getSumQuantities() {
		return sumQuantities;
	}

	public void setSumQuantities(int sumQuantities) {
		this.sumQuantities = sumQuantities;
	}

	public int getCountProduct() {
		return countProduct;
	}

	public void setCountProduct(int countProduct) {
		this.countProduct = countProduct;
	}

	public double getAvgPrice() {
		return avgPrice;
	}

	public void setAvgPrice(double avgPrice) {
		this.avgPrice = avgPrice;
	}

}

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.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import entities.Group;

public class ProductModel {

	public List<Group> groupBy() {
		List<Group> groups = new ArrayList<Group>();
		try {
			PreparedStatement preparedStatement = ConnectDatabase.getConnection().prepareStatement("select manufacturer, min(price) as minPrice, max(price) as maxPrice, sum(quantity) as sumQuantities, count(id) as countProduct, avg(price) as avgPrice from product group by manufacturer");
			ResultSet resultSet = preparedStatement.executeQuery();
			while (resultSet.next()) {
				Group group = new Group();
				group.setManufacturer(resultSet.getString("manufacturer"));
				group.setMinPrice(resultSet.getBigDecimal("minPrice"));
				group.setMaxPrice(resultSet.getBigDecimal("maxPrice"));
				group.setSumQuantities(resultSet.getInt("sumQuantities"));
				group.setCountProduct(resultSet.getInt("countProduct"));
				group.setAvgPrice(resultSet.getDouble("avgPrice"));
				groups.add(group);
			}
		} catch (Exception e) {
			groups = null;
		}
		return groups;
	}

}

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 entities.Group;
import models.ProductModel;

public class Main {

	public static void main(String[] args) {

		ProductModel productModel = new ProductModel();
		for(Group group : productModel.groupBy()) {
			System.out.println(group.getManufacturer());
			System.out.println("Min Price: " + group.getMinPrice());
			System.out.println("Max Price: " + group.getMaxPrice());
			System.out.println("Avg Price: " + group.getAvgPrice());
			System.out.println("Count Product: " + group.getCountProduct());
			System.out.println("Sum Quantities: " + group.getSumQuantities());
			System.out.println("==============================");
		}

	}

}

Output

Manufacturer 1
Min Price: 2.0
Max Price: 12.0
Avg Price: 7.0
Count Product: 2
Sum Quantities: 12
==============================
Manufacturer 2
Min Price: 4.0
Max Price: 21.0
Avg Price: 11.66667
Count Product: 3
Sum Quantities: 16
==============================
Manufacturer 3
Min Price: 17.0
Max Price: 32.0
Avg Price: 24.5
Count Product: 2
Sum Quantities: 10
==============================