How to retrieve data "At or Before" with "Interpolated" data?

Currently using PI SQL Commander 2021 with the RTPQ engine. (Really loving the performance increase switching from PI OLEDB to PI SQL Client.) I created a view to contain all static attributes. I created a Table-Valued Function to contain data that can be interpolated. Using a "Cross Apply" works great retrieving the desired data.

SELECT e.[Name], e.[Static Attribute 1], e.[Static Attribute 2], e.[Static Attribute 13], s.[TimeStamp], s.[Interpolated value 1], s.[Interpolated value 2], s.[Interpolated value 3]

FROM[Master].[Element].[DeviceX ] e

CROSSAPPLY[Master].[Element].[DeviceX_GetSampledValues]

(

    e.ID,--Element ID

'y',--Start Time

't',--End Time

'1h'--Time Step

) s

 

Now I want to add data that should not be interpolated but should be "At or Before" such as discrete values. Suggestions please.