problem 1 added

[Tejas274]

No description provided.

[super30admin]

The student's solution correctly solves the problem of finding the first login date for each player from the activity table. The solution uses the MIN() function to find the earliest event_date for each player_id, which is the standard approach for this type of problem. The GROUP BY clause correctly groups the results by player_id, and the ORDER BY ensures the output is sorted by player_id.

Strengths:

1. Correct use of SQL aggregate function MIN() to find the first login date
2. Proper grouping with GROUP BY player_id
3. Clear and readable SQL syntax with appropriate indentation
4. Includes ordering of results which is good practice

Areas for Improvement:

1. While not necessary for correctness, adding a comment explaining the purpose of the query would improve maintainability
2. The query could be made more explicit by using column aliases (though the current 'as first_login' is good)
3. Consider adding a LIMIT clause if only a sample of results is needed, though this depends on requirements

Time Complexity: O(n log n) due to the GROUP BY operation which typically requires sorting
Space Complexity: O(n) as it needs to store intermediate grouped results