refactor 1294

Author: fishercoder1534

Diff for: database/_1294.sql

@@ -1,89 +1,3 @@
---1294. Weather Type in Each Country
---
---Table: Countries
---
---+---------------+---------+
---| Column Name   | Type    |
---+---------------+---------+
---| country_id    | int     |
---| country_name  | varchar |
---+---------------+---------+
---country_id is the primary key for this table.
---Each row of this table contains the ID and the name of one country.
---
---
---Table: Weather
---
---+---------------+---------+
---| Column Name   | Type    |
---+---------------+---------+
---| country_id    | int     |
---| weather_state | varchar |
---| day           | date    |
---+---------------+---------+
---(country_id, day) is the primary key for this table.
---Each row of this table indicates the weather state in a country for one day.
---
---
---Write an SQL query to find the type of weather in each country for November 2019.
---
---The type of weather is Cold if the average weather_state is less than or equal 15, Hot if the average weather_state is greater than or equal 25 and Warm otherwise.
---
---Return result table in any order.
---
---The query result format is in the following example:
---
---Countries table:
---+------------+--------------+
---| country_id | country_name |
---+------------+--------------+
---| 2          | USA          |
---| 3          | Australia    |
---| 7          | Peru         |
---| 5          | China        |
---| 8          | Morocco      |
---| 9          | Spain        |
---+------------+--------------+
---Weather table:
---+------------+---------------+------------+
---| country_id | weather_state | day        |
---+------------+---------------+------------+
---| 2          | 15            | 2019-11-01 |
---| 2          | 12            | 2019-10-28 |
---| 2          | 12            | 2019-10-27 |
---| 3          | -2            | 2019-11-10 |
---| 3          | 0             | 2019-11-11 |
---| 3          | 3             | 2019-11-12 |
---| 5          | 16            | 2019-11-07 |
---| 5          | 18            | 2019-11-09 |
---| 5          | 21            | 2019-11-23 |
---| 7          | 25            | 2019-11-28 |
---| 7          | 22            | 2019-12-01 |
---| 7          | 20            | 2019-12-02 |
---| 8          | 25            | 2019-11-05 |
---| 8          | 27            | 2019-11-15 |
---| 8          | 31            | 2019-11-25 |
---| 9          | 7             | 2019-10-23 |
---| 9          | 3             | 2019-12-23 |
---+------------+---------------+------------+
---Result table:
---+--------------+--------------+
---| country_name | weather_type |
---+--------------+--------------+
---| USA          | Cold         |
---| Austraila    | Cold         |
---| Peru         | Hot          |
---| China        | Warm         |
---| Morocco      | Hot          |
---+--------------+--------------+
---Average weather_state in USA in November is (15) / 1 = 15 so weather type is Cold.
---Average weather_state in Austraila in November is (-2 + 0 + 3) / 3 = 0.333 so weather type is Cold.
---Average weather_state in Peru in November is (25) / 1 = 25 so weather type is Hot.
---Average weather_state in China in November is (16 + 18 + 21) / 3 = 18.333 so weather type is Warm.
---Average weather_state in Morocco in November is (25 + 27 + 31) / 3 = 27.667 so weather type is Hot.
---We know nothing about average weather_state in Spain in November so we don't include it in the result table.
-
---# Write your MySQL query statement below
 select c.country_name as country_name,
 case
 when avg(weather_state) <= 15 then "Cold"