When you perform a "run now" action on a monitor (to run it once as a test), the data will be written to the SV_TimeSeriesData table. If you look for a specific "run now" time stamp, you'll get an idea of the contents of that table. It will also help to identify the primary keys within that table, so you can retrieve results by project etc.
A copy of the SilkCentral Performance Manager schema can be downloaded as a .gif image file from:
HELP | DOCUMENTATION | PERFORMANCE MANAGER DATABASE SCHEMA