today another notice. Acumatica can provide values in two modes: merged and read-only.
So, what is merged? Imagine that user worked about the form, and made some changes at grid. Will changes apper in DB? Untill will be executed Persist, not. Data will be only in cache. Some time it is useful to compare data in cache with data in db. In order to get merged data you can use PXSelectReadOnly type or PXSelectGroupBy. For merged results you can use PXSelect or PXSelectJoin.