# LeetCode 1795. Rearrange Products Table

## Description

https://leetcode.com/problems/rearrange-products-table/

SQL Schema

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:

```Products table:
+------------+--------+--------+--------+
| product_id | store1 | store2 | store3 |
+------------+--------+--------+--------+
| 0          | 95     | 100    | 105    |
| 1          | 70     | null   | 80     |
+------------+--------+--------+--------+

Result table:
+------------+--------+-------+
| product_id | store  | price |
+------------+--------+-------+
| 0          | store1 | 95    |
| 0          | store2 | 100   |
| 0          | store3 | 105   |
| 1          | store1 | 70    |
| 1          | store3 | 80    |
+------------+--------+-------+

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.```

## Explanation

select each store and union all.

## SQL Solution

``````# Write your MySQL query statement below
select product_id, 'store1' as store, store1 as price
from Products
WHERE store1 IS NOT NULL
union all
select product_id, 'store2' as store, store2 as price
from Products
WHERE store2 IS NOT NULL
union all
select product_id, 'store3' as store, store3 as price
from Products
WHERE store3 IS NOT NULL``````