IshaSQL
Foundations Track · Easy · 15 min
Percentage of Users Attended a Contest
Table: Users +-------------+---------+ | Column Name | Type | +-------------+---------+ | user_id | int | | user_name | varchar | +-------------+---------+ u...
Company labels are directional practice context, not official interview guidance.
Objective
Practice aggregation through a IshaSQL-tagged business scenario.
Approach
Use this track to lock in clean query structure, basic filtering logic, and confidence with grouped output.
Company context
Company labels are directional practice context, not official interview guidance.
Table: Users +-------------+---------+ | Column Name | Type | +-------------+---------+ | user_id | int | | user_name | varchar | +-------------+---------+ user_id is the primary key (column with unique values) for this table. Each row of this table contains the name and the id of a user. Table: Register +-------------+---------+ | Column Name | Type | +-------------+---------+ | contest_id | int | | user_id | int | +-------------+---------+ (contest_id, user_id) is the primary key (combination of columns with unique values) for this table. Each row of this table contains the id of a user and the contest they registered into. Write a solution to find the percentage of the users registered in each contest rounded to two decimals . Return the result table ordered by percentage in descending order . In case of a tie, order it by contest_id in ascending order . The result format is in the following example. Example 1: Input: Users table: +---------+-----------+ | user_id | user_name | +---------+-----------+ | 6 | Alice | | 2 | Bob | | 7 | Alex | +---------+-----------+ Register table: +------------+---------+ | contest_id | user_id | +------------+---------+ | 215 | 6 | | 209 | 2 | | 208 | 2 | | 210 | 6 | | 208 | 6 | | 209 | 7 | | 209 | 6 | | 215 | 7 | | 208 | 7 | | 210 | 2 | | 207 | 2 | | 210 | 7 | +------------+---------+ Output: +------------+------------+ | contest_id | percentage | +------------+------------+ | 208 | 100.0 | | 209 | 100.0 | | 210 | 100.0 | | 215 | 66.67 | | 207 | 33.33 | +------------+------------+ Explanation: All the users registered in contests 208, 209, and 210. The percentage is 100% and we sort them in the answer table by contest_id in ascending order. Alice and Alex registered in contest 215 and the percentage is ((2/3) * 100) = 66.67% Bob registered in contest 207 and the percentage is ((1/3) * 100) = 33.33%
Users
Register
SQL workspace
Run queries against the protected question data, then submit once the result shape looks right.
Sign in to run SQL
Create a free account or sign in before running queries against protected question data.