Interview question

What is JDBC and what are the steps to connect Java to a database? JDBC क्या है और Java को database से connect करने के steps क्या हैं?

Answer

JDBC (Java Database Connectivity) is a standard Java API that lets applications interact with relational databases using SQL, regardless of which database vendor is used underneath.

Step	Action
1	Load the JDBC driver (auto-loaded via SPI since Java 6+)
2	Establish a Connection using DriverManager
3	Create a Statement/PreparedStatement
4	Execute the SQL query
5	Process the ResultSet
6	Close resources (Connection, Statement, ResultSet)

import java.sql.*;

public class JdbcExample {
    public static void main(String[] args) {
        String url = 'jdbc:mysql://localhost:3306/mydb';
        String user = 'root';
        String password = 'password';

        try (Connection conn = DriverManager.getConnection(url, user, password);
             Statement stmt = conn.createStatement();
             ResultSet rs = stmt.executeQuery('SELECT id, name FROM users')) {

            while (rs.next()) {
                int id = rs.getInt('id');
                String name = rs.getString('name');
                System.out.println(id + ': ' + name);
            }
        } catch (SQLException e) {
            System.out.println('Database error: ' + e.getMessage());
        }
        // try-with-resources closes Connection, Statement, and ResultSet automatically
    }
}

JDBC (Java Database Connectivity) एक standard Java API है जो applications को SQL इस्तेमाल करके relational databases से interact करने देता है, चाहे कोई भी database vendor हो।

Step	Action
1	JDBC driver load करना
2	DriverManager से Connection बनाना
3	Statement/PreparedStatement बनाना
4	SQL query execute करना
5	ResultSet process करना
6	Resources close करना

import java.sql.*;

public class JdbcExample {
    public static void main(String[] args) {
        String url = 'jdbc:mysql://localhost:3306/mydb';
        String user = 'root';
        String password = 'password';

        try (Connection conn = DriverManager.getConnection(url, user, password);
             Statement stmt = conn.createStatement();
             ResultSet rs = stmt.executeQuery('SELECT id, name FROM users')) {

            while (rs.next()) {
                int id = rs.getInt('id');
                String name = rs.getString('name');
                System.out.println(id + ': ' + name);
            }
        } catch (SQLException e) {
            System.out.println('Database error: ' + e.getMessage());
        }
    }
}

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