HP 3000 Manuals HP 3000 Manuals
C : What Are Tables?
Tables are data structures. The information contained in a table is
organized as rows and columns. This format is the basis for relational
databases. If you are familiar with a spreadsheet application, then you
are probably used to this kind of table format.
Typically, each column heading contains the name of the data item below
it. Each row represents a collection of related data items called a
record. For example:
PRODUCT-NBR WAREHOUSE
DES001 Fresno
DES002 Fresno
DES005 Austin
FIL001 Austin
This simple example illustrates the type of information often displayed
in a table. Here, a small portion of SAMPL2 is shown: A product number
(PRODUCT-NBR) and its associated warehouse location (WAREHOUSE).
In this particular table, all items and product numbers are unique.
Typically, each record is unique. Duplicate records are often omitted.
Since the information extracted by Access Server comes from an IMAGE
database, each record will be unique in at least one column, assuming all
significant columns are used in the configured table. However, this will
not necessarily be the case if the data comes from a file.
Table formats permit useful operations, which include:
* Mathematical operations (e.g., one column entry times another).
* Joins/Productions (e.g., combining two datasets from two different
databases to create another view of the information).
Such operations are performed by defining view tables, so called because
they create a "new view" of the information. View table creation can be
as simple as renaming column headings, or as complex as using a
mathematical formula on selected items from multiple databases.
Access Server returns all requested information in table format.