This Leetcode problem Queries Quality and Percentage LeetCode Solution is done in SQL.

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Queries Quality and Percentage LeetCode Solution

Problem Statement

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:

Output:

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

Queries Quality and Percentage LeetCode Solution MySQL

select 
  q.query_name, 
  round(
    ifnull(
      avg(rating / position), 
      0
    ), 
    2
  ) as quality, 
  round(
    ifnull(
      cnt / count(q.rating) * 100, 
      0
    ), 
    2
  ) as poor_query_percentage 
from 
  Queries as q 
  left join (
    select 
      query_name, 
      count(*) as cnt 
    from 
      Queries 
    where 
      rating < 3 
    group by 
      query_name
  ) as p on q.query_name = p.query_name 
group by 
  q.query_name;Code language: SQL (Structured Query Language) (sql)

Queries Quality and Percentage LeetCode Solution MySQL (Another approach)

select 
  query_name, 
  round(
    avg(rating / position), 
    2
  ) as quality, 
  round(
    avg(
      if(rating < 3, 1, 0)
    ) * 100, 
    2
  ) as poor_query_percentage 
from 
  Queries 
group by 
  query_name;Code language: SQL (Structured Query Language) (sql)