feat: problem 1 and 2 added

problem1-1045-customer-who-bought-all-products.sql

@@ -0,0 +1,13 @@
+with customer_product_purchase as (
+    select
+        customer_id,
+        count(distinct product_key) as cnt
+    from
+        customer
+    group by customer_id
+)
+
+select customer_id
+from
+    customer_product_purchase
+where cnt = (select count(product_key) from product)

problem2-1070-Product-Sales-Analysis-III.sql

@@ -0,0 +1,21 @@
+with product_sale_year as (
+    select
+        product_id,
+        year as first_year,
+        quantity,
+        price,
+        dense_rank() over (
+            partition by product_id
+            order by year
+        ) as rnk
+    from
+        sales
+)
+
+select
+    product_id,
+    first_year,
+    quantity,
+    price
+from product_sale_year
+where rnk = 1