Simple MySQL solution using UNION SELECT
\n# Write your MySQL query statement below\nSELECT product_id,"store1" as store,store1 as price\nFROM Products\nWHERE store1 IS NOT NULL\nUNION SELECT product_i
```\n# Write your MySQL query statement below\nSELECT product_id,"store1" as store,store1 as price\nFROM Products\nWHERE store1 IS NOT NULL\nUNION SELECT product_id,"store2",store2\nFROM Products\nWHERE store2 IS NOT NULL\nUNION SELECT product_id,"store3",store3\nFROM Products\nWHERE store3 IS NOT NULL;\n```
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