81. Days Between Subscription Dates

SQLite stores dates as TEXT, so to get a number of days between two dates you convert both to Julian day numbers with julianday(x) and subtract.

Task: for each subscription return id, signup, cancelled, and days_active — the whole number of days between signup and cancelled (cancelled - signup). Both columns are plain 'YYYY-MM-DD' dates, so the difference is already an integer; cast it to an integer with CAST(... AS INTEGER). Order by id.

Output columns, in order: id, signup, cancelled, days_active.