We will start by giving a definition of data warehousing, and then we'll go on to explore the definition by comparing and contrasting the features of a data warehouse with the features of operational systems that we have already described.
The accepted definition of a data warehouse (attributed to Bill Inmon, 1992) is a database that contains the following four characteristics:
Subject oriented means that the data is organized around subjects (such as Sales) rather than operational applications (such as order processing). Operational databases are organized around business application; they are application oriented.
Recall the five queries that the directors have identified ...