UPDATE [DR_HeatPumpCalc].[dbo].[tbl_lkupHeatPumps]
  if @Filetype <> '' SET [ImageFilename] ='heatpump-' + Convert(varchar(50),@NewHeatPumpID) + @Filetype,
  else SET [ImageFilename] = NULL
  if @PDFFiletype <>'' [PDFDatasheetPath] = 'heatpump-' + Convert(varchar(50),@NewHeatPumpID) + @PDFFiletype
  else [PDFDatasheetPath] = NULL
WHERE [HeatPumpID] = @NewHeatPumpID	

UPDATE [DR_HeatPumpCalc].[dbo].[tbl_lkupHeatPumps]
  SET [ImageFilename] =CASE WHEN @Filetype <> '' THEN 'heatpump-' + Convert(varchar(50),@NewHeatPumpID) + @Filetype ELSE NULL END,
[PDFDatasheetPath] = CASE WHEN @PDFFiletype <>''  THEN 'heatpump-' + Convert(varchar(50),@NewHeatPumpID) + @PDFFiletype ELSE NULL END
WHERE [HeatPumpID] = @NewHeatPumpID