Write SQL for first share and closest collaborator

You are given event data about users viewing design files.

Assume the following tables:

• files(file_id, creator_id)
  • creator_id is a VARCHAR user identifier.
• file_views(file_id, user_id, viewed_at)
  • user_id is an INTEGER user identifier.
  • Each row means user_id viewed file_id at time viewed_at.

A “share” is inferred when someone other than the creator views a file.

1. First share time per creator

Write a SQL query that returns, for each creator, the first time they ever shared a file they created (i.e., the earliest viewed_at where a non-creator viewed one of their files).

Output columns:

• creator_id
• first_shared_at

Notes:

• A creator viewing their own file should not count.
• creator_id (VARCHAR) and user_id (INTEGER) are different types; handle casting appropriately.

2. Closest collaborator model

For each file, define the “first person it was shared with” as the earliest non-creator viewer of that file (based on viewed_at).

Build a query/model that, for each creator, finds their closest collaborator, defined as the user who was the “first person shared with” for the creator’s files the most times.

Output columns:

• creator_id
• closest_collaborator_user_id
• collaborator_value (the number of files for which this collaborator was the first non-creator viewer)

Tie-breaking: if multiple collaborators have the same collaborator_value, choose the one with the earliest first-share timestamp across those tied records (and if still tied, the smallest user id).