For a Type 2 slowly changing dimension (SCD), you typically need to add the following types of columns that do not exist in the source system:
An effective start date and time (E): This column records the date and time from which the data in the row is effective.
An effective end date and time (A): This column indicates until when the data in the row was effective. It allows you to keep historical records for changes over time.
A surrogate key (C): A surrogate key is a unique identifier for each row in a table, which is necessary for Type 2 SCDs to differentiate between historical and current records.