c# - How to get the values from a column in Excel in uppercase after putting them into a DataTable -

i trying values column 18, test uppercase after upload of excel file without succes.

how can reach values in datatable?

this fill datatable values excel file:

 using (oledbdataadapter adapter = new oledbdataadapter(command))         {             datatable datatable = new datatable();             adapter.fill(datatable);             return datatable;         } 

i have values in 18 uppercase.

loop through rows making 18th columns data uppercase:

foreach (datarow row in datatable.rows) {     row["test"] = row["test"].tostring().toupper(); }