ALTER TABLE materials
  ADD COLUMN IF NOT EXISTS unit_label VARCHAR(60) NULL AFTER price,
  ADD COLUMN IF NOT EXISTS payment_methods TEXT NULL AFTER unit_label,
  ADD COLUMN IF NOT EXISTS price_note VARCHAR(190) NULL AFTER payment_methods;

UPDATE materials
SET unit_label = 'أمبير',
    payment_methods = 'نقد\nأقساط',
    price_note = 'السعر يحسب حسب الأمبير والتجهيزات المطلوبة'
WHERE slug = 'solar-energy';

UPDATE materials
SET unit_label = COALESCE(unit_label, 'كمية'),
    payment_methods = COALESCE(payment_methods, 'نقد\nأقساط')
WHERE unit_label IS NULL OR payment_methods IS NULL;