Hi,
Try this:
Declare @Entity as nvarchar(4)
Set @Entity = ( select min(T0.[Segment_1]) from OACT T0 where T0.[Segment_1] = '[%0]')
Declare @startdate as datetime
Set @startDate = (Select min(ta.Docdate) from OINV ta where ta.Docdate >='[%1]')
Declare @Enddate as datetime
Set @EndDate = (Select max(tb.Docdate) from OINV tb where tb.Docdate <='[%2]')
Thanks & Regards,
Nagarajan