/*
View: unpaid_ar_balances

Columns:
    card_no int
    old_balance (calculated)
    recent_payments (calculated)

Depends on:
    ar_history (table)

Depended on by:
  unpaid_ar_today (view)

Use:
This view lists A/R balances older than
20 days and payments made in the last 20 days.

The logic is pretty WFC-specific, but the 
general idea is to notify customers that they
have a balance overdue at checkout

*//* --COMMENTS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    * 24Oct2012 Eric Lee Comments Add Depended on by:, code style

*/