Working and architecture of data warehouse model: In data warehousing concept of query processing and decision making database model, reformatted business data is put in a database known as the warehouse. This warehouse is used to process business queries. Changed or new data is extracted and transformed in a timely fashion. SQL and data is sent and returned from DBMS to Data analysis and reports tools. Then this Data analysis and reports tools is used to send the processed data to the computer system. LAN database server, UNIX database server, and mainframe system is used to connect to the Customer database, product database and inventory respectively. Since all the business and analytical processing is taken care by the warehouse, data warehousing model is very successful. Apart from enterprise level data warehouses, small data warehouses known as data marts are also used. Data warehousing is used in manufacturing industries, telecommunications companies, airlines, and other financial services companies.