Table Schema
Inspect
Table
| Column | Type | Description |
|---|---|---|
| candidate_id | integer | Unique candidate identifier. |
| skill | varchar | A skill listed on the candidate profile. |
Data
Science
Skills
Find candidates who have all three required skills for a Data Science role: Python, Tableau, and PostgreSQL.
Inspect
Sample Data
Input
Output
Sample Input: candidates
| candidate_id | skill |
|---|---|
| 123 | Python |
| 123 | Tableau |
| 123 | PostgreSQL |
| 234 | R |
| 234 | PowerBI |
| 234 | SQL Server |
| 345 | Python |
| 345 | Tableau |
Expected Output
| candidate_id |
|---|
| 123 |
SQL Editor
Run
Query
Waiting for query
| candidate_id |
|---|
| 123 |
Hints
Unlock
Clues
Hint 01: First, filter rows to Python, Tableau, and PostgreSQL.
Hint 02: Group the filtered rows by candidate_id.
Hint 03: A qualified candidate has COUNT(skill) = 3, then order by candidate_id ASC.
Solution
Locked
Answer
Solution is locked until you decide to reveal it. Try the editor first, then open this when you want the reference answer.
SELECT
candidate_id
FROM candidates
WHERE skill IN ('Python', 'Tableau', 'PostgreSQL')
GROUP BY candidate_id
HAVING COUNT(skill) = 3
ORDER BY candidate_id ASC;Explanation
Step By
Step
01
Filter to the three skills required for the Data Science role.
02
Group by candidate_id so each candidate becomes one group of matching skills.
03
Use HAVING COUNT(skill) = 3 to keep candidates with all required skills, then sort ascending.
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