I need a LinQ Query for getting the data from one column and if data is not present in that column it must check it in second column and if not in second than check for the third column and write the data in another excel sheet

I need to check the data from one column that is a date column and if date is not present in the column than check into second column and add the data into new excel file.
I have tried a link query but getting the error mentioned below:

Argument Value “CopytoDatatable” is not a member of System.Data.EnumerableRowCollection(of object)
Also I have attached the Image for the error I am getting

Please Guide me over this.

Hi , You have neither specified any column name in this or in any other column .

The Query should be something like this to check the column .
dttemp.AsEnumerable().Where(datecolumn<> “”).CopyToDataTable