SCD (Slowly changing dimensions) that provides different attributes that are used for the record that varies over time and doesn't remain stable.

There are three types of SCDs are used in data warehousing. These are defined as:

SCD1: This is the record that is used to replace the original record even there is only one record exists in the database. The current data will be replaced and the new data will take its place.

SCD2: This is the new record file that is added to the dimension table. This record exists in the database with the current data and previous data that is stored in the history.

SCD3: This uses the original data that is modified to the new data. This consists of two record one record that exist in the database and another record that will replace the old database record with the new information.