CREATE TABLE IF NOT EXISTS wallet_transactions (
    id INT AUTO_INCREMENT PRIMARY KEY,
    user_id INT NOT NULL,
    amount DECIMAL(15,2) NOT NULL,
    type ENUM('add', 'withdraw', 'investment_out', 'investment_in') NOT NULL,
    description VARCHAR(255),
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
);