New question added in sql-quiz.ts

Summary of changes

Added a new question related to SQL.

[x] I have read and followed the contribution guidelines.
[x] I have read through the Code of Conduct and agree to abide by the rules.
[x] This PR is for one of the available issues and is not a PR for an issue already assigned to someone else.
[x] My PR title has a short descriptive name so the maintainers can get an idea of what the PR is about.
[x] I have provided a summary of my changes.