Using the candidate table, find the candidates who have all three of these skills:
Return a single column, candidate_id, and sort by candidate_id.
Hints
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Hint 1
Start from candidate and keep only the rows where skill is one of the three required ones.
Think of a filter with a list of values.
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Hint 2
A candidate can appear in multiple rows, one for each skill.
So group by candidate_id.
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Hint 3
After the GROUP BY, use a condition on the groups.
You need to count how many different skills remain for each candidate.