This article discusses the structural differences between relational databases optimized for online data transaction and data warehouses optimized for processing and summarizing large amounts of data. It also explores the differences between database requirements for operational data and decision support data, and provides examples of databases used to support decision making in large scale industries such as business and management, agricultural production, and forest management. Additionally, the article provides examples of data warehouses and data mining being used to support data processing and trend analysis in large organizational environments, such as education and healthcare.