The data present in the dimensional table changes from time to time. For example, the customer is staying in India for two years and then he moved to the USA here all his dimensional information will be changed.

 Like Address, Phone Number, Zip Code, and so on. 

By taking this as consideration slowly changing dimensions are categorized into 3 types. 

•  SCD Type 1
•  SCD Type 2
•  SCD Type 3 

SCD Type 1: In this type, all updates will be treated as Inserts.

SCD Type 2: Here it maintains the complete history. All updates will be treated as updates and inserts will be treated as inserts. 

SCD Type 3: It maintains a one-time history. 

Data present in the dimensional tables will be reported and analyzed with respect to the data present in the fact tables. 

However, the data present in the dimensional table keep changing from time to time something like address change, phone number change, customer or vendor moved from one location to another location, etc. 

All these factors influence the data present in the dimensional table. 

In order to maintain accurate data in the data warehouse, we got 3 types of dimensional tables based on their behavior. 

These are called SCD type 1, SCD type2, and SCD type3.

These tables being used in the data warehouse based on our business scenario and requirements, we use the appropriate dimensional types and models to achieve specific business goals. 

Hope you are clear.