In a Type 1 slowly changing dimension, which of the following best captures the required action to reflect changes in non-key attributes?

• A. Preserve the old value in a separate history record.
• B. Update non-key attributes in the existing row only.
• C. Insert a new row with a new surrogate key for every change.
• D. Update rows when non-key attributes have changed and insert new records when natural key has a new value.

Answer: (D)

In a Type 1 slowly changing dimension, you keep the latest values by updating the existing row’s non-key attributes whenever they change, and you don’t preserve history for those attributes. But when the natural (business) key itself changes, you can’t simply mutate that identity in the same row; you insert a new row with a new surrogate key to represent the new key value as a distinct record. So, the action aligns with updating non-key attributes in place to reflect their changes, and, if the natural key changes, creating a new row for the new key. This captures both the in-place refresh of attributes and the creation of a new record when the business key evolves.