Just gimme the code! Here’s an example of a percent change calculation:
And here’s the SQL used to generate it: 
ROW_NUMBER() OVER (
  PARTITION BY
    ${orders.order_date_month}
  ORDER BY
    ${orders.total_order_amount} DESC
)
In general, the SQL used for calculating the rank in a column has just one important column and one other important parameter:
  • column_i_want_to_rank - this is the column that you want to rank
  • ASC and DESC - if you want to have the biggest values with rank = 1, then you need to add DESC to your ORDER BY clause. If you want the smallest values with rank = 1 then you can add ASC to your ORDER BY clause (this isn’t required, since the ordering is ASC by default).

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Here’s the SQL you can copy-paste to calculate your rank in column

ROW_NUMBER() OVER (
  ORDER BY
    ${table.column_i_want_to_rank} DESC
)