WINDOW-Solution
Intuition\nWe can use window-function to get the first year. This part we just put to CTE.\nAfter that we can find answers comparing current year and the first 
# Intuition\nWe can use window-function to get the first year. This part we just put to CTE.\nAfter that we can find answers comparing current year and the first year\n\n# Code\n```\nWITH helper AS \n(\n    SELECT Sales.* ,\n        FIRST_VALUE(year) OVER (PARTITION BY product_id ORDER BY product_id, year) first_year\n    FROM Sales    \n)\nSELECT \n    product_id,\n    first_year,\n    quantity,\n    price\nFROM helper\nWHERE year = first_year;\n```
['Sliding Window', 'PostgreSQL']