Inherited description: Fetch the next row of data from the query.
qHandle is query-defined data and is typically updated by Fetch.
The Fetch method should set Row to be a $List of
values corresponding to the columns of the query. If we are past the end of the data
and no row is returned, Row should be set to null string ("").
If the non-empty row being returned is the last one, AtEnd could be
optionally set to 1, indicating that an additional call to Fetch may be avoided.
Row may also be subscripted. If any of the columns in the row are stream orefs
then the oref type information is lost in the Row $list encoded value. To retain
the oref type, place the oref into Row(0,columnNumber). %Library.ResultSet recognizes
this form and will extract the column value as the subscripted value.
Inherited description: Prepare the query for execution. For static queries, this method probably just
returns $$$OK. For dynamic queries this method will set up the information
returned by GetInfo. It is used by the various ResultSet objects.