Mock SQL 2

CustomersWho.sql

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+
+select customer_id
+from customer
+group by customer_id
+having count(distinct product_key)=(select count(product_key) from product);

ProductAnalysis.sql

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+
+-- Solution 1
+
+select product_id, year as first_year, quantity, price
+from (
+    select s.product_id, s.year, s.quantity, s.price,
+           DENSE_RANK() over (partition by product_id order by year) as rnk
+    from sales s
+) ranked
+where rnk = 1;
+
+-- Solution 2
+
+select s.product_id,newtab.first_year,s.quantity,s.price
+from (select product_id, min(year) as first_year
+     from sales
+     group by product_id) as newtab
+join sales s
+on newtab.product_id=s.product_id and newtab.first_year=s.year;

README.md

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-# Mock_SQL2
+# Mock_SQL2
+