How to append one DataTable to another DataTable

Merge takes a DataTable, Load requires an IDataReader - so depending on what your data layer gives you access to, use the required method. My understanding is that Load will internally call Merge, but not 100% sure about that.

If you have two DataTables, use Merge.

The datatype in the same columns name must be equals.

dataTable1.Merge(dataTable2);

After that the result is:

dataTable1 = dataTable1 + dataTable2

You could let your DataAdapter do the work. DataAdapter.Fill(DataTable) will append your new rows to any existing rows in DataTable.