Simply speaking, BI is the capability of analyzing the data of a datawarehouse in advantage of that business. A BI tool analyzes the data of a datawarehouse and to come into some business decision depending on the result of the analysis.

Ware House Mangement is So Important in the Large number of Data's Handling Part.For Ex.In Ms.Access ,we can store 100 Thosand data Consistently and can be retrived.Same like Each and Every DB having them Own Speciality.From various DB number Columns like more than 200 Column ,Data Retrive is not so easy through SQL & PL&SQL.Lots lines should write.In this case to maintain the data the DWH is So important.Especialy for Banking,Insurance,Telecom,Business etc.