Introduction to JDBC

July 01, 2025

JDBC, or Java Database Connectivity, is a Java API that allows Java applications to interact with relational databases. Introduced as part of Java Standard Edition, JDBC provides a standard interface for connecting to databases, executing SQL queries, and processing the results, making it an essential tool for any Java developer working with data-driven applications.

Why JDBC Matters

Modern applications often need to store, retrieve, and manipulate data. JDBC acts as the bridge between your Java application and a relational database like MySQL, Oracle, SQL Server, or PostgreSQL. By using JDBC, developers can perform CRUD (Create, Read, Update, Delete) operations directly from Java code using SQL.

JDBC is database-agnostic: by switching the JDBC driver, the same Java code can connect to different relational databases with minimal changes.

How JDBC Works

At its core, JDBC involves a few key components:

✅ Driver Manager

Manages the list of database drivers and establishes connections.

✅ Connection

Represents a session with a specific database.

✅ Statement

An interface for sending SQL queries to the database.

✅ ResultSet

A table of data representing the results of a query.

✅ Driver

A library provided by the database vendor that implements JDBC interfaces and enables Java apps to talk to that specific database.

Basic JDBC Workflow

Here’s a simple step-by-step process of how to use JDBC:

1️⃣ Load the JDBC Driver

Before you can connect, you must load the appropriate driver class into memory:

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

This tells the Java application which driver to use (in this case, MySQL).

2️⃣ Establish a Connection

Use DriverManager.getConnection() with the database URL, username, and password:

Connection conn = DriverManager.getConnection(

"jdbc:mysql://localhost:3306/mydb", "root", "password");

3️⃣ Create a Statement

Statements let you send SQL commands to the database:

Statement stmt = conn.createStatement();

4️⃣ Execute SQL Queries

For queries that return data (e.g., SELECT):

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

For updates (INSERT, UPDATE, DELETE):

int rowsAffected = stmt.executeUpdate("UPDATE employees SET salary=5000 WHERE id=1");

5️⃣ Process Results

Loop through the ResultSet to read rows:

while (rs.next()) {

int id = rs.getInt("id");

String name = rs.getString("name");

System.out.println("ID: " + id + ", Name: " + name);

}

6️⃣ Close Resources

Always close ResultSet, Statement, and Connection to avoid memory leaks:

rs.close();

stmt.close();

conn.close();

PreparedStatement: Safe and Efficient

For dynamic queries and protection against SQL injection, use PreparedStatement instead of Statement. For example:

PreparedStatement ps = conn.prepareStatement(

"SELECT * FROM employees WHERE id = ?");

ps.setInt(1, 1);

ResultSet rs = ps.executeQuery();

Prepared statements also improve performance by allowing the database to reuse execution plans for repeated queries.

Conclusion

JDBC is a fundamental API for Java developers working with databases. It gives you a standard way to connect, execute SQL, and process results, regardless of the underlying database. Mastering JDBC is a key step toward building reliable, data-driven Java applications.

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