DataTable dt;
String connectionString = @"Provider=Microsoft.Jet.Oledb.4.0;Data Source=C:\om.xls;Extended Properties=Excel 8.0";

query = @" SELECT [a].[f1], [a].[f2] FROM  [COMPLETED$] a";

dt = ExcelWorksheetToDataTable(query, connectionString);

SELECT [a].[f1], [a].[f2], getStatus([a].f1, [a].[f2]) as [Status]
FROM  [COMPLETED$] a;

        public static DataTable getProcessing(DataTable dt, string statusDefault = "")
        {
            dt = deleteHead(dt);
            dt = renameColumns(dt);
            dt = status(dt, statusDefault);

            return dt;
        }