HP 3000 Manuals

Up and Running with ALLBASE/SQL

Understanding the Process 

Designing a database to be built with ALLBASE/SQL means examining the
data you wish to store and then putting it into a form that ALLBASE/SQL
can understand.  In other words, you look at the logical relationships
that exist within the data and then create a relational design (tables,
views, indexes, etc.).  The process can be complex, and you could use a
number of formal design methodologies.  However, you can get a good first
approximation by using an intuitive approach, which is sketched very
briefly in this chapter.

Database design is the subject of much theoretical discussion and debate,
but everyone agrees that good design results in good performance.  Good
database design also gives you the greatest flexibility in formulating
your queries and in restructuring your databases when that becomes
necessary.  For these reasons, time spent on analysis and design "up
front" results in time and money saved in developing a production system.

A reading list at the end of this chapter provides references to
additional information.  If you are about to embark on a complex design,
be sure to consult this material.

A Small Sample Database 

To examine some data modeling techniques, let's imagine a small sample
database.  Suppose a radio station wants to create a database of
classical music recordings for use by program directors and announcers.
The station needs this information to plan a schedule of broadcasts, to
maintain a log of what is played, and to publish a monthly listener's
guide.  Here are some specific data items that will be needed:

   *   Recording company and date recorded.
   *   Album title.
   *   Album price.
   *   Medium.
   *   List of selections and timings.
   *   Total timing of each album.
   *   Names of orchestra, conductor, singers, accompanists.
   *   Composer's name, birthplace, and dates of birth and death.
   *   Comments on composers, albums, and selections.
   *   Date, time, and announcer for each selection played.

You can probably think of other items of information that might be useful
(for example, the date the album was acquired), but let's use these for
now.  How should this data be organized?


            

How Will the Data Be Used? 

A typical user of the database would be the program director, who might
ask questions like the following:

       What selections do I have by Beethoven that are less than 20
       minutes long?

       What did we broadcast last year on Beethoven's birthday?

       How many different versions of Beethoven's Fifth Symphony do we
       have, who are the conductors, and what are the timings?

       What composers represented in our library were born in March?

       What selections did George play last Tuesday morning on his
       chamber music show?

MPE/iX 5.0 Documentation