Done SQL3

[sakshiasati17]

Completed three question , one isn't solved yet in class will update once thats taught.

[super30admin]

The student's solution is completely empty, which means it fails to address the problem in any way. Since we don't have the problem description, we can't determine what the correct approach should be, but submitting an empty solution is never acceptable.

For future attempts, the student should:

1. Always attempt to solve the problem, even if partially
2. Include comments explaining their thought process if they're stuck
3. Ask clarifying questions if the problem statement is unclear
4. At minimum, provide a function signature or basic structure showing they understand what's being asked

Without any code, we cannot evaluate correctness, time/space complexity, code quality, or efficiency.