About Variables, Parameters, and Columns

In the Oracle Life Sciences Data Hub (Oracle LSH) a Variable is the definition source for both Table Columns and Parameters. Its attributes include data type, length, name, default value, and Nullable (Yes/No). These attributes form the basis of both Columns and Parameters; both Columns and Parameters are instances of Variables. Both have additional attributes. Parameters also serve as definitions for Parameter instances, making the only three-level definitional relationship among Oracle LSH objects.

You can use the same Variable as the definition source for multiple Columns and Parameters. This promotes consistency and compatibility: for example, if you base the Study Column of all Tables in a single data flow on the Study Variable, and the Study Parameter of all the Programs that read from and write to those Tables on the same Variable, the Columns and Parameters have the same data type and length, and Nullable setting.

The Nullable attribute, whose default value is Yes in a Variable, is expressed in opposite ways in the user interface for Columns and for Parameters. When you see a Variable whose Nullable attribute is set to Yes through a Column, you see a Nullable setting whose default value is Yes, like the Variable's. When you see the same Variable through a Parameter definition, you see a Required setting whose default value is No. This is the same attribute setting expressed in different ways: if a Variable is Nullable, it is not Required; if it is Required, it is not Nullable.