Java JDBC Connection with Oracle

In this tutorial, we will explore how to establish a JDBC connection with an Oracle database in Java. We will cover the steps to set up the Oracle database, establish a connection using JDBC, and perform basic operations such as inserting and querying data.

Introduction

What is JDBC?

Java Database Connectivity (JDBC) is an API that enables Java applications to interact with databases. It provides methods to query and update data in a database, as well as to retrieve metadata about the database itself.

Oracle Database

Oracle Database is a multi-model database management system produced and marketed by Oracle Corporation. It is one of the most widely used databases in the world, known for its robustness, scalability, and security features.

Table of Contents

1. Setting Up the Oracle Database
2. Adding Oracle JDBC Driver to Your Project
3. Establishing a Database Connection
4. Executing SQL Queries
5. Retrieving Data
6. Closing the Connection
7. Conclusion

1. Setting Up the Oracle Database

First, ensure you have an Oracle database installed and running. Create a database user and a table for demonstration purposes. Use the Oracle SQL*Plus or any Oracle database client to execute the following commands:

CREATE USER jdbc_user IDENTIFIED BY jdbc_password;

GRANT CONNECT, RESOURCE TO jdbc_user;

CREATE TABLE products (
    id NUMBER GENERATED BY DEFAULT AS IDENTITY,
    name VARCHAR2(100),
    description VARCHAR2(255),
    price NUMBER(10, 2),
    PRIMARY KEY (id)
);

2. Adding Oracle JDBC Driver to Your Project

To interact with an Oracle database, you need to add the Oracle JDBC driver to your project. If you are using Maven, add the following dependency to your pom.xml file:

<dependency>
    <groupId>com.oracle.database.jdbc</groupId>
    <artifactId>ojdbc8</artifactId>
    <version>19.8.0.0</version>
</dependency>

3. Establishing a Database Connection

We will start by establishing a connection to the Oracle database using JDBC.

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

public class JDBCOracleExample {
    private static final String URL = "jdbc:oracle:thin:@localhost:1521:orcl";
    private static final String USER = "jdbc_user";
    private static final String PASSWORD = "jdbc_password";

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }

    public static void main(String[] args) {
        try (Connection connection = getConnection()) {
            if (connection != null) {
                System.out.println("Connected to the Oracle database!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

4. Executing SQL Queries

We can use the Connection interface to create a Statement object and execute SQL queries. Here, we will insert a record into the products table.

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;

public class InsertProductExample {
    public static void main(String[] args) {
        String insertSQL = "INSERT INTO products (name, description, price) VALUES ('Laptop', 'Dell Inspiron', 75000.00)";

        try (Connection connection = JDBCOracleExample.getConnection();
             Statement statement = connection.createStatement()) {
            int rowsInserted = statement.executeUpdate(insertSQL);
            System.out.println(rowsInserted + " row(s) inserted!");
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

5. Retrieving Data

We can use the Connection interface to create a Statement object and execute a query to retrieve data from the products table.

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class SelectProductExample {
    public static void main(String[] args) {
        String selectSQL = "SELECT * FROM products";

        try (Connection connection = JDBCOracleExample.getConnection();
             Statement statement = connection.createStatement();
             ResultSet resultSet = statement.executeQuery(selectSQL)) {

            while (resultSet.next()) {
                int id = resultSet.getInt("id");
                String name = resultSet.getString("name");
                String description = resultSet.getString("description");
                double price = resultSet.getDouble("price");

                System.out.println("ID: " + id + ", Name: " + name + ", Description: " + description + ", Price: " + price);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

6. Closing the Connection

Using the try-with-resources statement ensures that the connection is closed automatically. This is important to free up database resources.

import java.sql.Connection;
import java.sql.SQLException;

public class CloseConnectionExample {
    public static void main(String[] args) {
        try (Connection connection = JDBCOracleExample.getConnection()) {
            if (connection != null) {
                System.out.println("Connected to the Oracle database!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Conclusion

In this tutorial, we have covered the basics of using the JDBC Connection interface to interact with an Oracle database. We demonstrated how to establish a connection, execute SQL queries, retrieve data, and close the connection using the try-with-resources statement. This guide should help you get started with JDBC and understand how to use the Connection interface effectively with Oracle.