QueryFieldDef Object
QueryFieldDef objects represent the fields you include in a QueryDef. Each QueryFieldDef object is a field in a QueryDef, each of which was created with the QueryDef.BuildField method.
The QueryFieldDef object includes methods for setting the sort order of a query.
A QueryFilterNode object represents one node in the query-expression
tree. A query expression consists of one or more QueryFilterNode objects arranged
hierarchically. The root node is created by the QueryDef object's BuildFilterOperator
method. The remaining nodes are all instances of the QueryFilterNode
class. Each node consists of one or more filters and a Boolean operator (specified
using the BoolOp constants
).