라이브 코딩테스트 뽀개기 Day1: Data Science Skills

Given a table of candidates and their skills, you're tasked with finding the candidates best suited for an open Data Science job. You want to find candidates who are proficient in Python, Tableau, and PostgreSQL.

Write a query to list the candidates who possess all of the required skills for the job. Sort the output by candidate ID in ascending order.

 

Assumption:

• There are no duplicates in the candidates table.

candidates Table:

Column	NameType
candidate_id	integer
skill	varchar

candidates Example Input:

candidate_id	skill
123	Python
123	Tableau
123	PostgreSQL
234	R
234	PowerBI
234	SQL Server
345	Python
345	Tableau

Example Output:

candidate_id

123

Explanation

Candidate 123 is displayed because they have Python, Tableau, and PostgreSQL skills. 345 isn't included in the output because they're missing one of the required skills: PostgreSQL.

The dataset you are querying against may have different input & output - this is just an example!

p.s. give the hints below a try if you're stuck and don't know where to start!

SELECT candidate_id
FROM candidates
WHERE skill IN ('Python', 'Tableau', 'PostgreSQL')
GROUP BY candidate_id
HAVING COUNT(DISTINCT skill) = 3;