1211. Queries Quality and Percentage

Description

Table: Queries

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| query_name  | varchar |
| result      | varchar |
| position    | int     |
| rating      | int     |
+-------------+---------+
This table 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 a solution to find each query_name, the quality and poor_query_percentage.

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

Return the result table in any order.

The result format is in the following example.

 

Example 1:

Input: 
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      |
+------------+-------------------+----------+--------+
Output: 
+------------+---------+-----------------------+
| query_name | quality | poor_query_percentage |
+------------+---------+-----------------------+
| Dog        | 2.50    | 33.33                 |
| Cat        | 0.66    | 33.33                 |
+------------+---------+-----------------------+
Explanation: 
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

Solutions

Solution 1: Grouping and Aggregation

We can group the query results by query_name, and then use the AVG and ROUND functions to calculate quality and poor_query_percentage.

MySQLMySQL

# Write your MySQL query statement below
SELECT
    query_name,
    ROUND(AVG(rating / position), 2) AS quality,
    ROUND(AVG(rating < 3) * 100, 2) AS poor_query_percentage
FROM Queries
WHERE query_name IS NOT NULL
GROUP BY 1;

# Write your MySQL query statement below
SELECT
    IFNULL(query_name, 'null') AS query_name,
    ROUND(AVG(CAST(rating AS DECIMAL) / position), 2) AS quality,
    ROUND(
        (
            SUM(
                CASE
                    WHEN rating < 3 THEN 1
                    ELSE 0
                END
            ) / NULLIF(COUNT(*), 0)
        ) * 100,
        2
    ) AS poor_query_percentage
FROM Queries
GROUP BY query_name WITH ROLLUP
HAVING query_name IS NOT NULL;

Comments