Before examining the various techniques available for design, let's think about the concept of data itself.
Organizations and enterprises use many assets, for example buildings, furniture, brains, but perhaps the most valuable asset is information or data. We remark that data documents the enterprise's procedures, and binds people into an ongoing exchange of information, called information flow. Computers help to formalize this data but we have to remember that it exists by itself.
When building data designs, we have to meet users and understand the enterprise's data flow. In an ideal world, every department, including the IT department, and every user would collaborate in order to help data flow easily between departments. However, from time to time, one can witness two attitudes that impede the normal data flow in enterprises. The first one is that some IT departments, having the responsibility for the computers where data resides, come to think that the data is theirs. This has the effect of keeping a certain level of secrecy that hides data and can block the data design process. The second one is a variation of the first one, this time caused by a user—data originates from this user and he has a tendency not to share it.
As an example of this latter attitude, let's consider accounting data. Before the PC era, accounting systems existed inside mainframes or minicomputers, and the IT department managed all data including accounting data. Since the advent of microcomputers and spreadsheet applications, an accounting clerk can manage a great deal of data, producing high-quality reports about it. However, this data often resides on his computer; he enters it, he produces the report, and he gets the accolades for it from his boss. So the data belongs to the accounting clerk, right? This way of thinking impedes data flow between individuals and departments and has a tendency of leading to redundant, disjoint data throughout the organization.
After the data design process, bridges are built between these isolated data islands created by users or departments so that the data can benefit the whole enterprise. It may also happen that fewer islands exist and redundant data is eliminated.