About Table Descriptors

Use Table Descriptors to map executable objects to the tables they read from and write to.

By having this table metadata in the executable object, you can map the executable to source and target table instances that are compatible in terms of column data type and length but that may not have exactly the same columns, table or column names, or column lengths as the tables the executable object was originally created to work with. This promotes reuse of Programs, Load Sets, Data Marts, and Business Areas.

In a Program definition's source code you refer to source and target Tables and Columns by the names of the Table Descriptors and their Columns, not the actual Table instances. In each instance of the Program you map the Table Descriptors to the Table instances they must read from or write to. You can have multiple instances of the same Program mapped to different source and target Table instances, and the Table instances may have different names or a different (but compatible) structure (see Mapping Columns of Different Data Types and Lengths).

For example, if Study 1 and Study 2 use demography tables with the same structure but called Demog in Study 1 and Demo in Study 2, you can create a single Program definition that reads from the demography table and creates several reports. You can create one instance of the Program that reads from the Study 1 Demog Table and another instance of the Program that reads from the Study 2 Demo Table.

Table Descriptors do not have constraints or data processing types. Different rules apply to source and target Table Descriptors.

Source Table Descriptor: A source Table Descriptor must be mapped to a Table instance that contains data to be used as input. You can map a source Table Descriptor to a Table instance located in any Work Area to which you have security access; in other words, your Program (or Data Mart or Business Area) can operate or report on data located anywhere in Oracle LSH where you have View privileges to Table instances.

For example, if you have a different Application Area for each clinical trial, you can pull data from each trial and combine data for a whole project by mapping the source Table Descriptors of the Program that combines the data to Table instances in the Work Area for each of the clinical trials.

The same Table instance can serve as a source for multiple Programs, Business Areas, and Data Marts.

Target Table Descriptor: A target Table Descriptor must be mapped to a Table instance that receives data output from a Program or Load Set. Target Table Descriptors must be mapped to a Table instance located in the same Work Area as the Program or Load Set instance.

Mapping Rules: The system enforces the following mapping rules:

• Only one Program can write to a Table instance; therefore only one target Table Descriptor can be mapped to a particular Table instance.
• A Table instance can be mapped to only one Table Descriptor in a Program instance.
• For additional rules, see Using Format Conversions and Mapping Columns of Different Data Types and Lengths.