Write a quarterly SQL report and a bash max-file script

Part A — SQL (conditional aggregation)

You have two tables:

• coins(coin_id, name)
• transactions(id, coin_id, dt, amount)

Write a query that returns one row per coin with the following columns:

• name
• q1_amount , q2_amount , q3_amount , q4_amount (sum of amount for transactions whose dt falls in quarter 1/2/3/4)
• total_transactions (count of transactions for that coin)
• total_amount (sum of amount for that coin)

Assume all transactions are within the same calendar year; if multiple years exist, state how you would filter to a target year.

Part B — Bash (filesystem)

Given a directory path, implement a shell function that returns the maximum file size (bytes) among all regular files under that directory.

Clarify whether the search is recursive; if not specified, assume recursive (include subdirectories). Handle the empty-directory case sensibly (e.g., return 0 or no output) and avoid counting directories.