Unit 5: Mengimplementasikan Pemrograman Terstruktur

<?php
// Fungsi dengan return value
function calculateDiscount($price, $discountPercent) {
    if ($discountPercent < 0 || $discountPercent > 100) {
        throw new InvalidArgumentException('Discount must be between 0 and 100');
    }
    
    return $price * ($discountPercent / 100);
}

// Prosedur (void function)
function displayProductInfo($product) {
    echo "<div class='product'>";
    echo "<h3>" . htmlspecialchars($product['name']) . "</h3>";
    echo "<p>Price: $" . number_format($product['price'], 2) . "</p>";
    echo "</div>";
}

// Fungsi dengan multiple parameters dan default values
function formatCurrency($amount, $currency = 'USD', $decimals = 2) {
    $symbols = [
        'USD' => '$',
        'EUR' => '€',
        'IDR' => 'Rp'
    ];
    
    $symbol = $symbols[$currency] ?? $currency;
    return $symbol . number_format($amount, $decimals);
}

// Usage examples
try {
    $originalPrice = 100;
    $discountAmount = calculateDiscount($originalPrice, 15);
    $finalPrice = $originalPrice - $discountAmount;
    
    $product = [
        'name' => 'Laptop Gaming',
        'price' => $finalPrice
    ];
    
    displayProductInfo($product);
    echo formatCurrency($finalPrice, 'IDR');
    
} catch (Exception $e) {
    error_log($e->getMessage());
    echo "An error occurred while processing the product.";
}
?>

-- Membuat database
CREATE DATABASE db_mahasiswa;
USE db_mahasiswa;

-- Membuat tabel mahasiswa
CREATE TABLE mahasiswa (
    id INT AUTO_INCREMENT PRIMARY KEY,
    nim VARCHAR(20) NOT NULL UNIQUE,
    nama VARCHAR(100) NOT NULL,
    email VARCHAR(100) NOT NULL UNIQUE,
    jurusan VARCHAR(50) NOT NULL,
    angkatan YEAR NOT NULL,
    alamat TEXT,
    tanggal_daftar TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    status ENUM('aktif', 'cuti', 'lulus', 'dropout') DEFAULT 'aktif'
);

-- Menambahkan index untuk performa
CREATE INDEX idx_jurusan ON mahasiswa(jurusan);
CREATE INDEX idx_angkatan ON mahasiswa(angkatan);

-- Contoh data sample
INSERT INTO mahasiswa (nim, nama, email, jurusan, angkatan, alamat) VALUES
('2023001001', 'Ahmad Muyassar', 'ahmad@email.com', 'Informatika', 2023, 'Makassar'),
('2023001002', 'Siti Nurhaliza', 'siti@email.com', 'Sistem Informasi', 2023, 'Jakarta'),
('2022001001', 'Budi Santoso', 'budi@email.com', 'Informatika', 2022, 'Surabaya');

<?php
// Database configuration
class DatabaseConfig {
    const HOST = 'localhost';
    const USERNAME = 'root';
    const PASSWORD = '';
    const DATABASE = 'db_mahasiswa';
    const CHARSET = 'utf8mb4';
}

// Database connection class
class Database {
    private $connection;
    
    public function __construct() {
        try {
            $dsn = "mysql:host=" . DatabaseConfig::HOST . 
                   ";dbname=" . DatabaseConfig::DATABASE . 
                   ";charset=" . DatabaseConfig::CHARSET;
            
            $options = [
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES => false,
            ];
            
            $this->connection = new PDO($dsn, DatabaseConfig::USERNAME, DatabaseConfig::PASSWORD, $options);
            
        } catch (PDOException $e) {
            error_log("Database connection failed: " . $e->getMessage());
            throw new Exception("Database connection failed");
        }
    }
    
    public function getConnection() {
        return $this->connection;
    }
    
    // Prepared statement untuk keamanan
    public function query($sql, $params = []) {
        try {
            $stmt = $this->connection->prepare($sql);
            $stmt->execute($params);
            return $stmt;
        } catch (PDOException $e) {
            error_log("Query failed: " . $e->getMessage());
            throw new Exception("Query execution failed");
        }
    }
    
    // Get single row
    public function fetchOne($sql, $params = []) {
        $stmt = $this->query($sql, $params);
        return $stmt->fetch();
    }
    
    // Get multiple rows
    public function fetchAll($sql, $params = []) {
        $stmt = $this->query($sql, $params);
        return $stmt->fetchAll();
    }
    
    // Get last inserted ID
    public function lastInsertId() {
        return $this->connection->lastInsertId();
    }
}

// Usage example
try {
    $db = new Database();
    
    // Test connection
    $result = $db->fetchOne("SELECT 'Connection successful' as message");
    echo $result['message'];
    
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
}
?>

<?php
class MahasiswaManager {
    private $db;
    
    public function __construct(Database $database) {
        $this->db = $database;
    }
    
    // CREATE - Tambah mahasiswa baru
    public function create($data) {
        try {
            // Validasi data
            $this->validateMahasiswaData($data);
            
            $sql = "INSERT INTO mahasiswa (nim, nama, email, jurusan, angkatan, alamat) 
                    VALUES (:nim, :nama, :email, :jurusan, :angkatan, :alamat)";
            
            $params = [
                ':nim' => $data['nim'],
                ':nama' => $data['nama'],
                ':email' => $data['email'],
                ':jurusan' => $data['jurusan'],
                ':angkatan' => $data['angkatan'],
                ':alamat' => $data['alamat'] ?? null
            ];
            
            $this->db->query($sql, $params);
            return $this->db->lastInsertId();
            
        } catch (Exception $e) {
            error_log("Create mahasiswa failed: " . $e->getMessage());
            throw new Exception("Gagal menambah data mahasiswa");
        }
    }
    
    // READ - Ambil data mahasiswa
    public function getAll($limit = 10, $offset = 0) {
        try {
            $sql = "SELECT * FROM mahasiswa ORDER BY nama ASC LIMIT :limit OFFSET :offset";
            $params = [':limit' => $limit, ':offset' => $offset];
            
            return $this->db->fetchAll($sql, $params);
            
        } catch (Exception $e) {
            error_log("Get all mahasiswa failed: " . $e->getMessage());
            throw new Exception("Gagal mengambil data mahasiswa");
        }
    }
    
    public function getById($id) {
        try {
            $sql = "SELECT * FROM mahasiswa WHERE id = :id";
            return $this->db->fetchOne($sql, [':id' => $id]);
            
        } catch (Exception $e) {
            error_log("Get mahasiswa by ID failed: " . $e->getMessage());
            throw new Exception("Gagal mengambil data mahasiswa");
        }
    }
    
    public function searchByName($name) {
        try {
            $sql = "SELECT * FROM mahasiswa WHERE nama LIKE :name ORDER BY nama ASC";
            $params = [':name' => '%' . $name . '%'];
            
            return $this->db->fetchAll($sql, $params);
            
        } catch (Exception $e) {
            error_log("Search mahasiswa failed: " . $e->getMessage());
            throw new Exception("Gagal mencari data mahasiswa");
        }
    }
    
    // UPDATE - Update data mahasiswa
    public function update($id, $data) {
        try {
            // Validasi data
            $this->validateMahasiswaData($data);
            
            $sql = "UPDATE mahasiswa SET 
                    nim = :nim, nama = :nama, email = :email, 
                    jurusan = :jurusan, angkatan = :angkatan, alamat = :alamat 
                    WHERE id = :id";
            
            $params = [
                ':id' => $id,
                ':nim' => $data['nim'],
                ':nama' => $data['nama'],
                ':email' => $data['email'],
                ':jurusan' => $data['jurusan'],
                ':angkatan' => $data['angkatan'],
                ':alamat' => $data['alamat'] ?? null
            ];
            
            $stmt = $this->db->query($sql, $params);
            return $stmt->rowCount() > 0;
            
        } catch (Exception $e) {
            error_log("Update mahasiswa failed: " . $e->getMessage());
            throw new Exception("Gagal mengupdate data mahasiswa");
        }
    }
    
    // DELETE - Hapus data mahasiswa
    public function delete($id) {
        try {
            $sql = "DELETE FROM mahasiswa WHERE id = :id";
            $stmt = $this->db->query($sql, [':id' => $id]);
            
            return $stmt->rowCount() > 0;
            
        } catch (Exception $e) {
            error_log("Delete mahasiswa failed: " . $e->getMessage());
            throw new Exception("Gagal menghapus data mahasiswa");
        }
    }
    
    // Validasi data mahasiswa
    private function validateMahasiswaData($data) {
        if (empty($data['nim']) || empty($data['nama']) || empty($data['email'])) {
            throw new InvalidArgumentException("NIM, Nama, dan Email wajib diisi");
        }
        
        if (!filter_var($data['email'], FILTER_VALIDATE_EMAIL)) {
            throw new InvalidArgumentException("Format email tidak valid");
        }
        
        if (!is_numeric($data['angkatan']) || $data['angkatan'] < 2000) {
            throw new InvalidArgumentException("Angkatan harus berupa tahun yang valid");
        }
    }
    
    // Get statistics
    public function getStatistics() {
        try {
            $sql = "SELECT 
                        COUNT(*) as total_mahasiswa,
                        COUNT(CASE WHEN status = 'aktif' THEN 1 END) as aktif,
                        COUNT(CASE WHEN status = 'lulus' THEN 1 END) as lulus,
                        jurusan,
                        COUNT(*) as jumlah_per_jurusan
                    FROM mahasiswa 
                    GROUP BY jurusan";
            
            return $this->db->fetchAll($sql);
            
        } catch (Exception $e) {
            error_log("Get statistics failed: " . $e->getMessage());
            throw new Exception("Gagal mengambil statistik");
        }
    }
}

// Usage example
try {
    $db = new Database();
    $mahasiswaManager = new MahasiswaManager($db);
    
    // Tambah mahasiswa baru
    $newMahasiswa = [
        'nim' => '2023001006',
        'nama' => 'Test User',
        'email' => 'test@email.com',
        'jurusan' => 'Informatika',
        'angkatan' => 2023,
        'alamat' => 'Test Address'
    ];
    
    $id = $mahasiswaManager->create($newMahasiswa);
    echo "Mahasiswa baru ditambahkan dengan ID: " . $id;
    
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
}
?>