Code:
Dim rCount
rCount = datatable.GetSheet("Global").GetRowCount
For i = 1 to rCount
DataTable.SetCurrentRow(i)
DataTable.Value("ColumnA", "Action1") = DataTable.Value("ColumnA", "Global")
DataTable.Value("ColumnB", "Action1") = DataTable.Value("ColumnA", "Global")
DataTable.Value("ColumnC", "Action1") = DataTable.Value("ColumnA", "Global")
NextThat should work!

