🗃️ Koneksi Java ke MySQL menggunakan JDBC

JDBC (Java Database Connectivity) adalah API resmi Java untuk mengakses database relasional seperti MySQL, PostgreSQL, dll.

Dengan JDBC, kamu bisa: - Terhubung ke database - Menjalankan perintah SQL (SELECT, INSERT, UPDATE, DELETE) - Mengambil hasil query - Mengelola transaksi

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🔧 Persiapan Awal

1. ✅ Pastikan MySQL aktif di komputer
2. ✅ Buat database: java_db
3. ✅ Tambahkan file JDBC driver (mysql-connector-j-*.jar) ke project (atau via Maven/Gradle)

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📦 Struktur Tabel Contoh

CREATE DATABASE java_db;

USE java_db;

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    nama VARCHAR(100),
    email VARCHAR(100)
);
````

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## 🔌 Koneksi JDBC: Langkah Dasar

```java
import java.sql.*;

public class Koneksi {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/java_db";
        String user = "root";
        String pass = "";

        try {
            Connection conn = DriverManager.getConnection(url, user, pass);
            System.out.println("Berhasil terkoneksi ke database!");
            conn.close();
        } catch (SQLException e) {
            System.out.println("Gagal koneksi: " + e.getMessage());
        }
    }
}

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📄 Menjalankan Query INSERT

String sql = "INSERT INTO users (nama, email) VALUES (?, ?)";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, "Marno");
ps.setString(2, "marno@email.com");
ps.executeUpdate();

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📄 Menjalankan Query SELECT

String sql = "SELECT * FROM users";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql);

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

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📄 Update & Delete

// Update
String sql = "UPDATE users SET nama = ? WHERE id = ?";
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, "Marno Update");
ps.setInt(2, 1);
ps.executeUpdate();

// Delete
String del = "DELETE FROM users WHERE id = ?";
PreparedStatement delps = conn.prepareStatement(del);
delps.setInt(1, 2);
delps.executeUpdate();

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📌 Best Practice JDBC

Tips	Penjelasan
Gunakan PreparedStatement	Hindari SQL Injection
Tutup koneksi setelah pakai	Gunakan try-with-resources bila perlu
Tangani SQLException	Log semua error dengan detail
Pooling koneksi (lanjutan)	Gunakan HikariCP/Apache DBCP di sistem besar

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🔁 Contoh Lengkap

public class UserDAO {
    private Connection conn;

    public UserDAO() throws SQLException {
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/java_db", "root", "");
    }

    public void tambahUser(String nama, String email) throws SQLException {
        String sql = "INSERT INTO users (nama, email) VALUES (?, ?)";
        PreparedStatement ps = conn.prepareStatement(sql);
        ps.setString(1, nama);
        ps.setString(2, email);
        ps.executeUpdate();
    }

    public void tampilkanSemua() throws SQLException {
        String sql = "SELECT * FROM users";
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(sql);

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

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📌 Kesimpulan

Langkah	Penjelasan
DriverManager	Mengelola koneksi ke database
Connection	Objek utama koneksi
Statement / PreparedStatement	Menjalankan SQL
ResultSet	Menampung hasil SELECT
Koneksi stabil	Tutup koneksi setelah selesai

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➡️ Selanjutnya: Collection Framework Lanjutan