To really understand business intelligence (BI) and
data warehouses (DW), it is necessary to look at the evolution of business
and technology.
In the 1970s and 1980s, computer hardware was expensive
and computer processing power was limited. A medium-sized business
typically operated a handful of large mainframe-based application systems
that were designed for operational, data entry purposes. Information needs
were addressed through paper reports. Report programs, however, were
expensive to write and generally inflexible. A computer programmer was
required to write the report programs. Fortunately, salaries for
programmers were relatively low during this period.
In the 1980s, relational databases became the rage.
Data was stored in tables with rows and columns, not unlike Excel
Spreadsheets of today. Although relational databases were much more
intuitive for end users, complex logic was often needed to join multiple
tables to obtain the information that was needed. Although it was possible
for end users to write simple reports, the queries were often inefficient
and had to be run after normal business hours, in order not to impact online
transactions.
In the late 1980s, many businesses migrated from
mainframe computers to client servers. Business people were assigned a
personal computer. Office applications such as MicroSoft World, Excel and
Access became popular. The personal computer empowered end users and
allowed them to develop their own applications and present data in a manner
that was meaningful to them, such as in grid or graph format. Excel
spreadsheets could easily be tweaked as business needs changed, without the
assistance from the IT department. Unfortunately, corporate data remained
centralized and was generally not directly accessible to end users.
