Table: Products
| Column Name | Type |
|---|---|
| product_id | int |
| store1 | int |
| store2 | int |
| store3 | int |
product_id is the primary key for this table. Each row in this table indicates the product’s price in 3 different stores: store1, store2, and store3. If the product is not available in a store, the price will be null in that store’s column.
Write an SQL query to rearrange the Products table so that each row has (product_id, store, price). If a product is not available in a store, do not include a row with that product_id and store combination in the result table.
Return the result table in any order.
The query result format is in the following example.
Example 1:
Input: Products table:
| product_id | store1 | store2 | store3 |
|---|---|---|---|
| 0 | 95 | 100 | 105 |
| 1 | 70 | null | 80 |
Output:
| product_id | store | price |
|---|---|---|
| 0 | store1 | 95 |
| 0 | store2 | 100 |
| 0 | store3 | 105 |
| 1 | store1 | 70 |
| 1 | store3 | 80 |
Explanation: Product 0 is available in all three stores with prices 95, 100, and 105 respectively. Product 1 is available in store1 with price 70 and store3 with price 80. The product is not available in store2.
SELECT product_id,
'store1' store,
store1 price
FROM Products
WHERE store1 IS NOT NULL
UNION ALL
SELECT product_id,
'store2' store,
store2 price
FROM Products
WHERE store2 IS NOT NULL
UNION ALL
SELECT product_id,
'store3' store,
store3 price
FROM Products
WHERE store3 IS NOT NULL;