Databases Reference
In-Depth Information
could be possible, though, because each would be used in a different table and
would result in a unique column name. Similarly, you add unnecessary confusion
if you use Serial Number in some tables and Employee Number in others to refer
to the same value. An even bigger problem arises if you use different identifying
values in different tables, making it difficult (if not impossible) to establish rela-
tionships between tables.
Another issue of data standards relates to data access. It's important to insist
on consistency in the way that programs access the database. These include
issues such as how connections are established, how data is retrieved, and how
data manipulation commands are passed. Here, the data administrator must
work with application programmers and the database administrator to develop
standards that help minimize problems relating to performance and security.
Also, well-established standards help to make application programs easier to
maintain when it comes time to make changes or add functionality.
Data standards also come into play in the IS interactions between companies
in supply chains, as shown in Figure 9-2. When data is exchanged using
elec-
tronic data interchange (EDI)
technology, technology used for electronic data
transfer and related data standards, adjustments have to be made to account for
data structure and other differences in the information systems of the two com-
panies involved.
Many companies use non-relational data formats for passing information
such as purchase orders. It's common to find XML documents based on prede-
fined schemas as the transfer standard. The need to be able to generate messages
in those formats can impact how database data is structured.
In Figure 9-2, you see a retailer sending a purchase order to the warehouse
using EDI technology. The order is received automatically by the computer at
Figure 9-2
Purchase Order
Retailer
Warehouse
Electronic data interchange (EDI).
