ETL (Extract, Transform and Load) is in the simplest terms the tools supporting the process of obtaining data for databases, especially for data warehouses. The purpose of these tools is: obtaining data from external sources (eg SAP, ERP, other transaction systems), data transformation (cleaning, filtering, data merging, column and row transpositions, data rejection) and loading data into a database (usually a wholesaler) data). Among the DCG specialists there are experts in the field of ETL who work with such tools as Informatica Power Center, Websphere DataStage, IBM Cognos or SQL Server Integration Services.