Is there any way I could add C# function as a Formula in a cell?
The use case is that I have to do a VLOOKUP on data which is in the database and lives outside the excel. Since I have potentially 100,000 rows of VLOOKUP data, is there a way to create a C# function which takes required CELL values to do a lookup?
Well, since your data is present in some external data sources and Aspose.Cells does not support to retrieve or manipulate data from external database to Excel sheet, so I am afraid, you got to first paste your data to Excel sheet via using your own .NET code and then you may use Aspose.Cells APIs to set or calculate VLOOKUP or any other function/ formula based on your selected values or range of cells in the sheet.
Furthermore, we do support ICustomFunction interface where you may implement your own custom functions by writing your own routines via Aspose.Cells APIs, see the document/ article for your complete reference: