Data warehousing Concepts - Slowly changing Dimensions

Hi all,
Here in this section, I will be going to give you a brief explanation on Slowly changing dimension.

Introduction:

As the name represents it, When a dimension changes over time we call it as  a Slowly changing dimension.  We can handle this type of situation in 3 types. these are

SCD type 1
SCD type 2
SCD type 3

Say for example consider the below example.



Customer-id   Customer-name         Address
      12              Kullayappa           Kuala Lampur


Now after some months the customer's adress has been changed to Singapore. and now the data looks like below.

Customer-id   Customer-name         Address
      12              Kullayappa             Singapore

SCD Type 1: 
How SCD type1 approach deals now is, remove the historical data that has been presented and have the updated data only. In this case we could not able to track the historical data.

Example:

Customer-id   Customer-name         Address
      12              Kullayappa             Singapore

SCD Type 2:
SCD type 2 prefers to add a another record for new entry and identify those new records on version.

Example:
Customer-id   Customer-name         Address                 Version
        12              Kullayappa             Kuala Lampur           0
        12              Kullayappa             Singapore                  1

SCD Type 3:
SCD type 3 suggest to add one more column for the new record instead of adding extra record.

Example:

Customer-id   Customer-name         Previous_Address      Current_Address
        12              Kullayappa             Kuala Lampur               Singapore




Folks, I have typed on my own and excuse for my typo errors , I am providing details as per my knowledge.