original question: how to makeup missing dates in a query.
solution: use a outer join between the table which contains data and another table contains only continuous dates.
Problem: how to get a column contains continuous dates in RQM.
Trick: In RQM data model (not in [Business View] which are queries from data model), each folder contains a "Date" data item. Drag a list to see the data, I found this "Date" contains continuous date from 12/31/99 to 12/31/55 (1999 to 2055 I guess). Add another query from this data item(and filter), then problem solved.
Note: the date item located at the leaf of the tree. It is something like [FOLDER].[Date].[Date].[Date].[Date]. I'm not familiar with these raw data yet. Need some time to look into it.