Percentage of Users Attended a Contest | Leetcode 1633 | Crack SQL Interviews in 50 Qs

[@learnwithchirag]

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[@arshlankhan1507]

why we did not use right join in this qus ? explain please

[@swatiriyal9242]

Easiest solution i could find on internet, Good work sir!

[@learnwithchirag]

Glad it helped !..Keep Learning 💯🎯

[@justcodeitbro1312]

if we are using group by then it will count the number of user_id in each group right ? no need of distinct worked for me without it

[@rishavrajsingh7660]

hello I'm having one question why you didn't use the join and how its even possible without join function?

[@skkrrtt2344]

# Write your MySQL query statement below SELECT r.contest_id, ROUND(COUNT(DISTINCT user_id)*100/(SELECT COUNT(user_id) from Users),2) as percentage FROM Users as u RIGHT JOIN Register as r USING(user_id) GROUP BY contest_id ORDER BY percentage DESC,r.contest_id; My solution

[@Nik_vlogs1]

Thanks very helpful

[@abhishekdhakne4879]

why didn't we use JOIN

[@learnwithchirag]

Yes , There can be multiple ways of solving an SQL question. Here is the query using JOIN- SELECT r.contest_id, ROUND((SUM(IF(r.user_id IS NOT NULL, 1, 0)) / (SELECT count(*) FROM users) * 100), 2) AS percentage FROM Register r LEFT JOIN users u ON u.user_id = r.user_id GROUP BY r.contest_id ORDER BY percentage DESC, r.contest_id ASC; The choice between using a join or not depends on the specific requirements of your query and the structure of your database. Both approaches are valid, and you should choose the one that best fits your needs and performs well with your database schema and data distribution.

[@akhilpratapsingh3223]

In this we should use right join na?@@learnwithchirag

[@sandhyarawat1768]

sir (SELECT count(*) FROM users) ki place me count(u.user_name) ya u.user_id likh sakte hai kya???? nahi to kyu nahi

[@sandeepvarma89]

​​@@sandhyarawat1768kar sakte hai dono ka answer same hi aayega count (*)from users Kiya toh total rows count honge jo hai 3, user_name count Kiya toh bhi 3 hi aayega,user_id bhi use kar sakte hai

[@redeagle6580]

invalid use of group by de rha

[@learnwithchirag]

Please do check your syntax again. The query is working perfectly fine for me !

[@karunakarverma6467]

TLE mar gya ye to

[@muhibajaz7156]

Solve this query with Join: SELECT r.contest_id, ROUND(COUNT(r.user_id) / (SELECT COUNT(*) FROM Users) * 100, 2) AS percentage FROM Register r LEFT JOIN Users u ON u.user_id = r.user_id GROUP BY r.contest_id ORDER BY percentage DESC, r.contest_id ASC;

[@abhijaychouhan5176]

SELECT contest_id, ROUND(COUNT(contest_id)*100/(SELECT COUNT(user_id) FROM Users), 2) AS percentage FROM Register GROUP BY contest_id ORDER BY percentage DESC, contest_id This code is running fine , even if I changed this "distinct user_id" to "contest_id" and why this code is more optimised HELP ME