Simple Solution Using UNION
\n# Write your MySQL query statement below\n# Pivot Function cannot be used as PIVOT >> ROWS to COLUMNS not vice versa\n# So we use UNION\n\nSELECT product_id, 
```\n# Write your MySQL query statement below\n# Pivot Function cannot be used as PIVOT >> ROWS to COLUMNS not vice versa\n# So we use UNION\n\nSELECT product_id, \'store1\' AS store, store1 AS price\nFROM Products\nWHERE store1 IS NOT NULL\n\nUNION\n\nSELECT product_id, \'store2\' AS store, store2 AS price\nFROM Products\nWHERE store2 IS NOT NULL\n\nUNION\n\nSELECT product_id, \'store3\' AS store, store3 AS price\nFROM Products\nWHERE store3 IS NOT NULL\n\n```
['Union Find', 'MySQL']