We can able to maintain old historical and current data (SCD) using the date column. Let me show you people how to write a small query to achieve it. For example, Assume we have a column called currency which has currency values of all the countries and your business needs it to keep it uniform, say convert all currency of different countries to USD, so it will be easy for Business judgement and analysis. For this, let me take an example of Yahoo! Finance . Yahoo! Finance API provides us currency conversion of all country based on time. I am not here going to tell how to pull the data from Yahoo! Finance API, But I am using such data which I pulled to explain how SCD can be achieved. Below is a image, which depicts, the data which we got from Yahoo! Finance. We wanted this to get converted as shown below: Where we wanted to derive Effective_To column, which indicates, from one date to other date, the currency was so & so for a country against USD. ...