What is JDBC? Explain different JDBC drivers.

 JDBC (Java Database Connectivity) is a standard API in Java that provides a way to access and manipulate relational databases using the Java programming language. With JDBC, you can connect to a database, execute SQL queries and updates, and retrieve and process the results.

There are four different types of JDBC drivers:

1. JDBC-ODBC Bridge Driver: This driver uses the ODBC (Open Database Connectivity) API to access the database. It requires a native library to be installed on the system and is only suitable for Windows-based systems.
2. Native API Driver: This driver uses the database's native API to access the database. It requires a native library to be installed on the system and is specific to the database being used.
3. Network Protocol Driver: This driver uses a middleware layer to communicate with the database over a network. It is suitable for accessing databases across different platforms and can be used for any database that provides a network protocol.
4. Thin Driver: This driver is a pure Java implementation that communicates directly with the database using a network protocol. It is suitable for accessing databases across different platforms and can be used for any database that provides a network protocol.

The choice of driver to use depends on your specific requirements and the database being used. The Thin Driver is the most commonly used driver because it is platform independent and does not require any native libraries to be installed.

Here's an example of using JDBC to retrieve data from a database:

import java.sql.*;
public class JDBCTest {
    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/mydatabase", "username", "password");
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM mytable");
            while (rs.next()) {
                String name = rs.getString("name");
                int age = rs.getInt("age");
                System.out.println("Name: " + name + ", Age: " + age);
            }
            rs.close();
            stmt.close();
            conn.close();
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }
}

In this example, we use the com.mysql.jdbc.Driver driver to connect to a MySQL database located on the local machine. We create a Statement object and execute a SQL query to retrieve all the rows from a table called mytable. We then process the results using a ResultSet object and print the name and age of each row to the console. Finally, we close the resources in reverse order.