LeetCode - 1211. Queries Quality and Percentage (SQL)

Welcome to the detailed solution and walkthrough for the SQL challenge 'Queries Quality and Percentage' from LeetCode.

Concepts Covered:
-- Aggregate Functions (SUM, COUNT): Understand the use of aggregate functions like SUM() and COUNT() to perform calculations over groups of data. This is essential for summarizing large datasets into meaningful metrics.
-- Conditional Aggregation: Learn about implementing conditional logic within aggregation, using a CASE statement. This is showcased by calculating the percentage of poor queries (where rating is less than 3).
-- Grouping Data with GROUP BY: Discover how to group your dataset by specific criteria using the GROUP BY clause. In this query, data is grouped by query_name, allowing for the calculation of metrics per query.

Whether you're prepping for interviews or refining your SQL skills, this solution will provide you with practical insights and a clearer understanding of some pivotal SQL techniques.

#sql #leetcode #coding #sqlforbeginners #developer #faang #interview

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[maamardR]

for the one who are facing a problem here is a HINT

What if there was NULL value on query_name, what can we do to not group it ?


the answer is :





WHERE query_name IS NOT NULL