Just gimme the code! Here’s an example of a rolling window:
And here’s the SQL used in the table calculation: 
SUM(${dbt_orders.count_distinct_order_id}) OVER (
  ORDER BY
    ${dbt_orders.order_date_week}
  ROWS BETWEEN 3 PRECEDING AND CURRENT ROW
) /
  SUM(${dbt_orders.count_distinct_user_id}) OVER (
    ORDER BY
      ${dbt_orders.order_date_week}
    ROWS BETWEEN 3 PRECEDING AND CURRENT ROW
  )
The SQL used for calculating rolling windows has at least two bits, with an optional third:
  • first_column_I_want_to_sum is the column with the values you want to add up (sometimes this is an average)
  • column_I_want_to_order_by is the column you want to order by when defining your lookback window
  • N is the number of previous rows you want to include in your calculation (don’t forget the current row is included, so for a four week lookback window, we’ll use N=3)
  • second_column_I_want_to_sum is optional, another column with values you want to add up to compare to your first column, like when calculating averages (which is how we use it in this example)

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Here’s the SQL you can copy-paste to calculate rolling windows

Make sure you swap out the columns AND choose a number value for N. 
SUM(${table.column_I_want_to_sum}) OVER (
  ORDER BY
    ${table.column_I_want_to_order_by}
  ROWS BETWEEN N PRECEDING AND CURRENT ROW
) /
  SUM(${table.second_column_I_want_to_sum}) OVER (
    ORDER BY
      ${table.column_I_want_to_order_by}
    ROWS BETWEEN N PRECEDING AND CURRENT ROW
  )