-- 1. Son aylar içinde sipariş vermeyen müşterilerin listesini çıkarın. -- Yapı: -- customers (customer_id, name, registration_date) -- orders (order_id, customer_id, order_date, amount) SELECT DISTINCT c.customer_id, c.name FROM customers c LEFT JOIN orders o ON c.customer_id = o.customer_id and o.order_date >= DATE_TRUNC('month', CURRENT_DATE) - INTERVAL '1 month') WHERE o.amount IS NULL -- 2. Her alt kategorinin toplam kategori gelirlerindeki payını hesaplayın -- sales (product_id, category, subcategory, revenue, sale_date) -- Sonuç: category | subcategory | share_of_category