Database Connectivity

In Java, JDBC (Java Database Connectivity) provides an API for connecting to relational databases, executing SQL queries, and processing results. It enables Java applications to interact with databases like MySQL, Oracle, PostgreSQL, and others.

Steps to Connect to a Database

  1. Load the Database Driver
    You need to load the database-specific driver class using Class.forName().

    Class.forName("com.mysql.cj.jdbc.Driver");


2. **Establish a Connection**
   Use the `DriverManager.getConnection()` method to establish a connection.

   ```java
   Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "user", "password");

  1. Create a Statement Create a Statement object to execute SQL queries.

    Statement stmt = conn.createStatement();

  2. Execute Queries Use executeQuery() for SELECT queries and executeUpdate() for INSERT, UPDATE, DELETE.

    ResultSet rs = stmt.executeQuery("SELECT * FROM users");

  3. Process Results Iterate over the ResultSet to process the data.

    while (rs.next()) {
    System.out.println(rs.getString("name"));
}

  4. Close Connections Close the ResultSet, Statement, and Connection to release resources.

    rs.close();
stmt.close();
conn.close();

Example Code for Database Connectivity

import java.sql.*;

public class DatabaseExample {
    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "root", "password");
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM users");

            while (rs.next()) {
                System.out.println("ID: " + rs.getInt("id") + ", Name: " + rs.getString("name"));
            }

            rs.close();
            stmt.close();
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

🔗 Related Notes