📘 Network Programming Concepts: JDBC (Java Database Connectivity)

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🔷 1. Definition

JDBC (Java Database Connectivity) is a Java API that allows Java programs to connect and interact with databases.

👉 It is used to:

• Execute SQL queries
• Retrieve and update data
• Communicate with databases over a network

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🔷 2. Key Concept

JDBC acts as a bridge between:

• Java Application
• Database (like MySQL, Oracle)

📊 Concept Diagram (Description) Java Program → JDBC API → JDBC Driver → Database

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🔷 3. JDBC Architecture

🔹 Components:

1. JDBC API

   • Provides classes and interfaces

2. JDBC Driver Manager

   • Manages database drivers

3. JDBC Driver

   • Converts Java calls into database-specific commands

4. Database

   • Stores data

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🔷 4. Types of JDBC Drivers

Type	Description
Type 1	JDBC-ODBC Bridge
Type 2	Native API
Type 3	Network Protocol
Type 4	Thin Driver (most used)

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🔷 5. Steps to Connect to Database

✔ Step-by-step:

1. Load Driver

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

2. Establish Connection

Connection con = DriverManager.getConnection(
    "jdbc:mysql://localhost:3306/mydb", "root", "password");

3. Create Statement

Statement stmt = con.createStatement();

4. Execute Query

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

5. Process Result

while(rs.next()) {
    System.out.println(rs.getInt(1) + " " + rs.getString(2));
}

6. Close Connection

con.close();

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🔷 6. Example Program

import java.sql.*;

public class JDBCExample {
    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");

            Connection con = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/mydb", "root", "password");

            Statement stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM student");

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

            con.close();
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

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🔷 7. Important JDBC Interfaces

Interface	Purpose
Connection	Connect to database
Statement	Execute SQL
PreparedStatement	Precompiled SQL
ResultSet	Store result

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🔹 PreparedStatement Example

PreparedStatement ps = con.prepareStatement(
    "INSERT INTO student VALUES (?, ?)");

ps.setInt(1, 1);
ps.setString(2, "Ali");

ps.executeUpdate();

👉 Advantages:

• Faster execution
• Prevents SQL injection

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🔷 8. Types of Statements

Type	Use
Statement	Simple SQL
PreparedStatement	Parameterized queries
CallableStatement	Stored procedures

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🔷 9. Exception Handling in JDBC

• Uses try-catch blocks
• Common exception: SQLException

catch(SQLException e) {
    System.out.println(e.getMessage());
}

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🔷 10. Transactions in JDBC

• Used for multiple operations
• Ensures data consistency

con.setAutoCommit(false);

// SQL operations

con.commit();   // save changes
con.rollback(); // undo changes

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🔷 11. Important Rules

• Always close connection
• Use PreparedStatement for security
• Handle exceptions properly
• Use transactions when needed

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🔷 12. Advantages of JDBC

• Platform independent
• Supports multiple databases
• Easy database connectivity
• Secure (with PreparedStatement)

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🔷 13. Diagram Description

📊 JDBC Working Diagram:

• Java Application
• JDBC API
• Driver Manager
• Database

Arrows showing flow of data and commands

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📝 Likely Exam Questions

1. What is JDBC? Explain its architecture.
2. Explain steps to connect Java with database.
3. What are types of JDBC drivers?
4. Difference between Statement and PreparedStatement.
5. What is ResultSet?
6. Write a JDBC program to fetch data.
7. Explain transaction management in JDBC.
8. What is SQLException?
9. What is the role of DriverManager?
10. Advantages of JDBC.

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📌 Quick Revision Summary

• JDBC = Java Database Connectivity

• Connects Java to database

• Steps:

  1. Load driver
  2. Connect
  3. Create statement
  4. Execute query
  5. Process result
  6. Close connection

• Use PreparedStatement for security

• Handle exceptions properly

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