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https://github.com/souzafcharles/jdbc-connection-to-postgresql

☕ Review content from DevSuperior on Object-Oriented Programming and SQL using Java, JDBC, and PostgreSQL
https://github.com/souzafcharles/jdbc-connection-to-postgresql

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☕ Review content from DevSuperior on Object-Oriented Programming and SQL using Java, JDBC, and PostgreSQL

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# :coffee: Object-oriented and SQL revision using Java and JDBC



:triangular_flag_on_post: Prof. Dr. Nelio Alves - [DevSuperior](https://devsuperior.com.br/)



:black_nib: IDE used: `IntelliJ IDEA`



:coffee: Java | version: `21`



:elephant: Database | `PostgresSQL`



***

## Instructions:



Develop a Java application that connects to a database using JDBC and interfaces following the DAO pattern, featuring entity classes for Order and Product. The target PostgresSQL database is chdeliver.



## Steps to Follow:



### 1. Database Configuration:

- Add the lib `postgresql-42.2.18.jar` to the project;

- Establish a database named `chdeliver` using `pgAdmin 4`;

- In the project's root folder, create a file named `db.properties` containing the connection data:



#### db.properties File:



```SQL

user=postgres

password=******

dburl=jdbc:postgresql://localhost:5432/chdeliver

useSSL=false

```

***

### 2. Database Table Creation:

- Create an SQL script to store data in the `chdeliver` database.

#### database.sql Script:

```SQL

-- Drop table 'tb_order_product' if it exists

DROP TABLE IF EXISTS tb_order_product;



-- Drop table 'tb_order' if it exists

DROP TABLE IF EXISTS tb_order;



-- Drop table 'tb_product' if it exists

DROP TABLE IF EXISTS tb_product;



-- Create table 'tb_order' if it does not exist

CREATE TABLE IF NOT EXISTS tb_order (

    id int8 generated by default as identity, 

    latitude float8, 

    longitude float8, 

    moment TIMESTAMP WITHOUT TIME ZONE, 

    status int4, 

    primary key (id)

);



-- Create table 'tb_order_product' if it does not exist

CREATE TABLE IF NOT EXISTS tb_order_product (

    order_id int8 not null, 

    product_id int8 not null, 

    primary key (order_id, product_id)

);



-- Create table 'tb_product' if it does not exist

CREATE TABLE IF NOT EXISTS tb_product (

    id int8 generated by default as identity, 

    description TEXT, 

    image_uri varchar(255), 

    name varchar(255), 

    price float8, 

    primary key (id)

);



-- Add foreign key constraints to 'tb_order_product' only if they do not exist

ALTER TABLE tb_order_product 

ADD CONSTRAINT fk_tb_order_product_tb_product 

FOREIGN KEY (product_id) REFERENCES tb_product;



ALTER TABLE tb_order_product 

ADD CONSTRAINT fk_tb_order_product_tb_order 

FOREIGN KEY (order_id) REFERENCES tb_order;



-- Insert data into 'tb_product'

INSERT INTO tb_product (name, price, image_uri, description) VALUES 

('Pizza de Calabresa Grande', 50.0, 'https://github.com/souzafcharles/1.png', 'Deliciosa pizza de calabresa com queijo muçarela, molho de tomate especial e orégano. Disponível em tamanho grande.'),

('Pizza Quatro Queijos Média', 40.0, 'https://github.com/souzafcharles/2.png', 'Uma explosão de sabores com queijo gorgonzola, queijo provolone, queijo parmesão e queijo muçarela. Ideal para compartilhar.'),

('Pizza de Escarola com Bacon Grande', 60.0, 'https://github.com/souzafcharles/3.png', 'Combinação perfeita de escarola refogada com bacon crocante, coberta com queijo muçarela e molho branco. Uma delícia!');



-- Insert data into 'tb_order'

INSERT INTO tb_order (status, latitude, longitude, moment) VALUES 

(0, 213123, 12323, TIMESTAMP WITH TIME ZONE '2025-01-14T11:00:00Z'),

(1, 3453453, 3534534, TIMESTAMP WITH TIME ZONE '2025-01-15T11:00:00Z');



-- Insert data into 'tb_order_product'

INSERT INTO tb_order_product (order_id, product_id) VALUES 

(1, 1),

(1, 2),

(2, 2),

(2, 3);

```

#### Tables:

![Tables](https://github.com/souzafcharles/JDBC-Connection-to-PostgreSQL/blob/main/img/tables.png)



***

### 3. Entities Classes:

- Create the `Order` and `Product` classes;



![Order and Product Entities](https://github.com/souzafcharles/JDBC-Connection-to-PostgreSQL/blob/main/img/order-product-entities.png)



#### Entities classes checklist:

- Attributes;

- Constructors;

- Getters/Setters;

- hashCode and equals;

- toString;

- Implements Serializable.

***

### 4. Tutorial Video Tests Checklist:

- Primary key and Foreign key;

- DDL (create table, alter table);

- SQL:

  - INSERT;

  - SELECT;

  - INNER JOIN;

- Classes and Objects;

- Encapsulation, get/set;

- Enumerated types;

- Object Composition;

- Collections (List and Map);

- Accessing data in a Relational Database and instantiating corresponding objects;

#### Query to retrieve Orders with their Products:

```SQL

SELECT * FROM tb_order

INNER JOIN tb_order_product ON tb_order.id = tb_order_product.order_id

INNER JOIN tb_product ON tb_product.id = tb_order_product.product_id

```

***

▶️ [Tutorial Video DevSuperior](https://www.youtube.com/watch?v=xC_yKw3MYX4&ab_channel=DevSuperior)

***

### 5. DAO Pattern (Data Access Object):

- Create the `ProductDAO` and `OrderDAO` interfaces following the `DAO Pattern`.

#### Generic DAO Class:

```java

public interface DAO {

    void insert(T obj);

    void update(T obj);

    void deleteById(Integer id);

    T findById(Integer id);

    List findAll();

}

```

- Implement the classes `OrderDAOJDBC` and `OrderDAOJDBC`.

- Create the `DAOFactory` to instantiate DAO objects.



![DaoFactory](https://github.com/souzafcharles/JDBC-Connection-to-PostgreSQL/blob/main/img/daoFactory.png)

***

### 6. CRUD Operations Implementation:

***

### 6.1. `findById` - Implement the search by `ID`:

#### App Class:

```java

System.out.println("\n********** TEST 01: Order findById **********");

OrderDAO orderDAO = DAOFactory.createOrderDAO();

Order order = orderDAO.findById(1);

System.out.println(order);



System.out.println("\n********** TEST 01: Product findById **********");

ProductDAO productDAO = DAOFactory.createProductDAO();     

Product product = productDAO.findById(2);

System.out.println(product);

```

#### Order SQL Query:

```SQL

SELECT tb_order.*, 

       tb_product.id AS ProductId, 

       tb_product.name AS ProductName, 

       tb_product.price AS ProductPrice, 

       tb_product.description AS ProductDescription, 

       tb_product.image_uri AS ProductImageUri 

FROM tb_order 

INNER JOIN tb_order_product ON tb_order.id = tb_order_product.order_id 

INNER JOIN tb_product ON tb_order_product.product_id = tb_product.id 

WHERE tb_order.id = 1;

```

#### Product SQL Query:

```SQL

SELECT * FROM tb_product 

WHERE id = 2;

```

***

### 6.2. `findAll` - Implement the search for `all` records:

#### App Class:

```java

System.out.println("\n********** TEST 02: Order findAll **********");

ListlistOrder = orderDAO.findAll();

for (Order o : listOrder) {

    System.out.println(o);

}



System.out.println("\n********** TEST 02: Product findAll **********");

List listProduct = productDAO.findAll();

for (Product p : listProduct) {

    System.out.println(p);

}

```

#### Order SQL Query:

```SQL

SELECT * FROM tb_order 

ORDER BY id;

```

#### Product SQL Query:

```SQL

SELECT * FROM tb_product 

ORDER BY name;

```

***

### 6.3. `insert` - Implement the `insertion` of new records:

#### App Class:

```java

System.out.println("\n********** TEST 03: Order insert **********");

Order newOrder = new Order(null, -23.555555, -46.666666, Instant.now(), OrderStatus.PENDING);

orderDAO.insert(newOrder);

System.out.println("Inserted! New Order id = " + newOrder.getId());



System.out.println("\n********** TEST 03: Product insert **********");

Product newProduct = new Product(null, "Pizza Margherita Deluxe", 35.0, "Uma pizza clássica Margherita com tomates frescos, manjericão, muçarela de búfala e um toque de azeite extra virgem.", "https://github.com/souzafcharles/4.png");

productDAO.insert(newProduct);

System.out.println("Inserted! New Department Name = " + newProduct.getName());

```

#### Order SQL Query:

```SQL

INSERT INTO tb_order (latitude, longitude, moment, status)

VALUES (?, ?, ?, ?)

```

#### Product SQL Query:

```SQL

INSERT INTO tb_product (name, price, image_uri, description)

VALUES (?,?,?,?)

``` 

***

### 6.4. `relation insert` - Implement the `Order-Product relation insert` of new records:



Add the method signature `insertOrderProductRelation` to the `OrderDAO` interface.



OrderDAO Interface Class:

```java

public interface OrderDAO extends DAO {

    void insertOrderProductRelation(Long orderId, Long productId);

}

```

#### App Class:

```java

System.out.println("\n********** TEST 04: Order-Product relation insert **********");

orderDAO.insertOrderProductRelation(newOrder.getId(), newProduct.getId());

System.out.println("Inserted! New relation between Order id = " + newOrder.getId() + " and Product id = " + newProduct.getId());

```

#### Order SQL Query:

```SQL

INSERT INTO tb_order_product (order_id, product_id)

 VALUES (?, ?)

***

```

***

### 6.5. `update` - Implement the `update` of existing records:

#### App Class:

```java

System.out.println("\n********** TEST 05: Order update **********");

order = orderDAO.findById(5);

order.setOrderStatus(OrderStatus.DELIVERED);

orderDAO.update(order);

System.out.println("Update completed!");



System.out.println("\n********** TEST 05: Product update **********");

product = productDAO.findById(4);

product.setPrice(45.0);

productDAO.update(product);

System.out.println("Update completed!");

```

#### Order SQL Query:

```SQL

UPDATE tb_order 

SET latitude = ?, longitude = ?, moment = ?, status = ? 

WHERE id = ?

```

#### Product SQL Query:

```SQL

UPDATE tb_product "

SET name = ?, price = ?, image_uri = ?, description = ?

WHERE id = ?

``` 

***

### 6.6. `delete` - Implement the `deletion` of records:

#### App Class:

```java

System.out.println("\n********** TEST 06: Order delete **********");

System.out.print("Enter the Order Id for deleteById test: ");

int id = scanner.nextInt();

orderDAO.deleteById(id);

System.out.println("Delete completed!");



System.out.println("\n********** TEST 06: Product delete **********");

System.out.print("Enter the Product Id for deleteById test: ");

id = scanner.nextInt();

productDAO.deleteById(id);

System.out.println("Delete completed!");

``` 

#### Order SQL Query (`tb_order_product`):

Delete references in the relationship table.

```SQL

DELETE FROM tb_order_product 

WHERE id = ?;

```

#### Product SQL Query (`tb_order_product`)::

Delete references in the relationship table.

```SQL

DELETE FROM tb_order_product

WHERE id = ?;

```

#### Order SQL Query:

Delete the Order.

```SQL

DELETE FROM tb_order 

WHERE id = ?;

```

#### Product SQL Query:

Delete the Product.

```SQL

DELETE FROM tb_product 

WHERE id = ?;

```



***

### 6.7. `find Orders Associated Products` - Implement the find `Orders` and their associated `Products`:



Add the method signature `findOrdersAssociatedProducts` to the `OrderDAO` interface.



OrderDAO Interface Class:

```java

public interface OrderDAO extends DAO {

  List findOrdersAssociatedProducts();

}

```

#### Associated Objects:

![Associated Objects](https://github.com/souzafcharles/JDBC-Connection-to-PostgreSQL/blob/main/img/associated-objects.png)



#### App Class:

```java



System.out.println("\n********** TEST 07: find Orders and their Associated Products**********");

List ordersWithProducts = orderDAO.findOrdersAssociatedProducts();

for (Order ord : ordersWithProducts) {

    System.out.println(ord);

    for (Product prod : ord.getProducts()) {

        System.out.println(prod);

    }

    System.out.println("******");

}

```

#### Order SQL Query:

```SQL

SELECT * FROM tb_order 

INNER JOIN tb_order_product ON tb_order.id = tb_order_product.order_id

INNER JOIN tb_product ON tb_product.id = tb_order_product.product_id

```