DW TIP: Get next or previous value with SQL Analytic Function [EN-US; PLSQL]

While querying our databases we might face a typical problema which is getting the next or the previous value of an atribute according to some rule applyed to a certain dataset. This happens more if you deal with datawarehouses and need to retrieve this kind of analytical information. The typical solutions involve several “group by” and sub queries to achieve the same result. This way SQL has a powerful feature  which are the Analytical functions.

Analytic functions compute an aggregate value based on a group of rows. They differ from aggregate functions in that they return multiple rows for each group. The group of rows is called a window and is defined by the analytic_clause. For each row, a sliding window of rows is defined. The window determines the range of rows used to perform the calculations for the current row. Window sizes can be based on either a physical number of rows or a logical interval such as time.



Handling Slow Changing Dimensions (SSIS2012)

This post will explain the following:

  • Slow changing dimensions (SCD0,SCD1,SCD2 and SCD3)
  • Inferred Members
  • How to configure a SCD component in a data flow using SSIS2012

Slow-Changing Dimensions are a special data warehouse modeling technique, that allow you to manage how your ETL process will resolve updates and inserts into a dimension, so that you can tell your packages what to do if an attribute value changes.