Multi row Variables

Hi:

In order to create multi row variables, attribute groups and attributes need to be previously defined. 

When creating attributes, these can be assigned to a value set but I would like to know how to assign a SQL statement in order to retrieve attribute values automatically.

For instance: If Attribute Group "Chapter" has been created for Item "Book" and the following attributes are defined: chapter number, name; Are attribute values entered manually when authoring contract terms or can they be automatically retrieved? 

Thanks in advance,

Beatriz