This diagram shows how a slowly changing dimension type 3 table is implemented.
customer_number is the business key of the customer table while customer_id is a surrogate key. Customer 10001 is changing first_name from Kontext to Context.
SCD Type 3 will add a new attribute to keep the current value. The drawback is that it can only keep previous and current values only.
For SCD Type 3, surrogate ID is not necessary.