Dataview filter for null values in a column using C#

Load data to DataTable from backend And Filter from Code behind

DataTable dt2= null,
  DataTable dt3= null,

strFilter = "ColumnName IS NOT NULL";
                        DataView dv = dt2.AsDataView();
                        dv.RowFilter = strFilter;
                        dt3= dv.ToTable();
                        dt3.AcceptChanges();