1211. Queries Quality and Percentage

https://leetcode.com/problems/queries-quality-and-percentage

Description

Table: Queries

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| query\_name  | varchar |
| result      | varchar |
| position    | int     |
| rating      | int     |
+-------------+---------+
There is no primary key for this table, it may have duplicate rows.
This table contains information collected from some queries on a database.
The position column has a value from **1** to **500**.
The rating column has a value from **1** to **5**. Query with rating less than 3 is a poor query.

We define query quality as:

The average of the ratio between query rating and its position.

We also define poor query percentage as:

The percentage of all queries with rating less than 3.

Write an SQL query to find each query_name, the quality and poor_query_percentage.

Both quality and poor_query_percentage should be rounded to 2 decimal places.

The query result format is in the following example:

Queries table:
+------------+-------------------+----------+--------+
| query\_name | result            | position | rating |
+------------+-------------------+----------+--------+
| Dog        | Golden Retriever  | 1        | 5      |
| Dog        | German Shepherd   | 2        | 5      |
| Dog        | Mule              | 200      | 1      |
| Cat        | Shirazi           | 5        | 2      |
| Cat        | Siamese           | 3        | 3      |
| Cat        | Sphynx            | 7        | 4      |
+------------+-------------------+----------+--------+
Result table:
+------------+---------+-----------------------+
| query\_name | quality | poor\_query\_percentage |
+------------+---------+-----------------------+
| Dog        | 2.50    | 33.33                 |
| Cat        | 0.66    | 33.33                 |
+------------+---------+-----------------------+
Dog queries quality is ((5 / 1) + (5 / 2) + (1 / 200)) / 3 = 2.50
Dog queries poor\_ query\_percentage is (1 / 3) * 100 = 33.33
Cat queries quality equals ((2 / 5) + (3 / 3) + (4 / 7)) / 3 = 0.66
Cat queries poor\_ query\_percentage is (1 / 3) * 100 = 33.33

ac