var results = from myRow in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;
//Reference System.Data.DataSetExtensions
//Be carefull to data types
int id = 1;
//one row
DataRow r = (from DataRow m in myTable.Rows where m.Field<int>("col_name") == id select m).FirstOrDefault();
//list of rows
List<DataRow> r = (from DataRow m in myTable.Rows where m.Field<int>("col_name") == id select m).ToList();