Use access definitions to specify the tables,
relationship traversal, and selection criteria for the data you want
to process.
An access definition includes the following items.
- Tables
- An access definition must reference at least one
table, view, alias, or synonym. The table, view, alias, or synonym
from which rows are selected first is called the start table. You
can enter the name of a start table and easily include the names of
all tables related to the start table (to a maximum of 24,000 tables).
- Start table
- The start table is the first table to use when extracting data.
You can specify any table in the access definition as the start table,
except a reference table. If you do not explicitly specify a start
table, the first table in the table list is the start table.
- Related table
- A related table is included based on a relationship to another
table in the access definition.
- Reference table
- A table from which all rows are selected, unless selection criteria
are specified. Specify any table as a reference table, except the
start table.
- Relationships
- Relationships determine the traversal path for
selecting data from tables. By default, relationships are traversed
from parent to child, but you can control the direction of traversal
using settings in the access definition. Relationships among tables
referenced by the access definition are listed on the relationship
tab (to a maximum of 24,000 tables). You can select relationships
to be used in processing and the direction in which they are traversed.
- Selection criteria
- Selection criteria define a specific set of data
to use from the tables in an access definition. You can specify SQL
operators and values, and use substitution variables with default
values.
- Point and shoot
- Use a point and shoot list to select specific rows from a start
table that will be included in a service.
- Variables
- Variables are user-defined default values specified in an access
definition. You can use these substitution variables to specify column
selection criteria or to create an SQL WHERE clause.
- Additional parameters
- Use additional parameters for extracting rows that
correspond to a particular column value in the start table or for
using a specified sampling rate (every nth row).
Naming conventions
A
fully qualified access definition name is in the form identifier.name,
where:
- identifier
- Qualifier assigned to the access definition (1 to
8 characters).
- name
- Base name assigned to the access definition (1 to
12 characters).
A logical set of naming conventions
can identify the use for each access definition and be used to organize
them for easy access.