CREATE TABLE IF NOT EXISTS accounting_periods (
    id INT AUTO_INCREMENT PRIMARY KEY,
    period_name VARCHAR(50) NOT NULL COMMENT 'e.g., January 2026',
    start_date DATE NOT NULL,
    end_date DATE NOT NULL,
    status ENUM('open', 'closed') NOT NULL DEFAULT 'open',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    UNIQUE KEY (start_date, end_date)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;