8. Write a cents_to_dollars Macro

Difficulty: Easy · Topic: Macros

Every model in the project converts cents to currency units by hand, each slightly differently. Write the macro cents_to_dollars(column_name, scale=2) in macros/cents_to_dollars.sql: it returns the SQL expression that divides the column by 100 and rounds the result to scale decimal places.

The model that calls it is fixed (you only write the macro):

select
    payment_id,
    {{ cents_to_dollars('amount_cents') }} as amount,
    {{ cents_to_dollars('fee_cents', 1) }} as fee
from {{ ref('stg_payments_raw') }}

Hidden tests call it in other ways too, such as scale=0 by keyword. A null column stays null.

Your model is compiled like dbt does and run in DuckDB against 3 test cases, including hidden edge cases.

Sample inputs

{{ ref('stg_payments_raw') }}

payment_id	amount_cents	fee_cents
1	1999	59
2	250	30
3	12345	null

Expected output

payment_id	amount	fee
1	19.99	0.6
2	2.5	0.3
3	123.45	null

Hints

Hint 1

{% macro cents_to_dollars(column_name, scale=2) %} ... {% endmacro %}. The body is the SQL text the call is replaced with.

Hint 2

Inside, {{ column_name }} prints the column name you were given and {{ scale }} the number: round({{ column_name }} / 100, {{ scale }}).

Hint 3

Use /, not //: in DuckDB // is integer division and drops the cents before rounding.

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