TS/MP Pathsend and Server Programming Manual (G06.24+, H06.03+)

Designing Your Application
NonStop TS/MP Pathsend and Server Programming Manual–132500
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Designing the Database
Designing the Database
The next step in developing a Pathway application is to design the database that will be
accessed and updated by the application. Designing the database, which is a highly
specialized activity typically performed by experienced database administrators,
involves:
•
Precisely identifying the meaning and use of the data as it exists in your business
and specifying the database files and records that will store this data. This step is
referred to as logical design.
•
Choosing file types and keys for the records. This step is referred to as physical
design.
In addition to completing a logical and physical design of your database, you must also
select a database manager product and ensure that your server programs can interface
with that database manager.
Logical Design
During the logical design process, you determine which classes of data must be
maintained by your application and identify the relationships that exist between the
classes. Each class of data names something that the database will store information
about. For example, in an application that processes sales orders, orders is a class of
data and order-items is a relationship between a particular order and the inventory
items within the order. These data classes and relationships generally become records in
files accessed by the application.
After specifying data classes, you list the attributes (data items) for each class of data.
For example, some of the attributes are order-ID, cust-ID, and order-total.
These attributes become fields in the records of the database. After specifying attributes
for data classes, you diagram the relationships between each of the files in the database
and then normalize your database files. To normalize files is to ensure, at a minimum,
that:
•
There are no repeating fields.
•
Data is dependent on the entire key (a unique element) of a field.
•
Data is dependent on nothing but the key.