string sql =" select vm.[units],sum(ts.[Dealmoney]),sum(vm.[onbaoxiao]),sum(vm.[nianbaoxiao]) from VehicMessage vm LEFT JOIN TecSystem ts on vm.card=ts.card group by vm.[card],vm.[units]";
OleDbCommand com = new OleDbCommand(sql); OleDbDataReader reader = com.ExecuteReader();-------报错，{"至少一个参数没有被指定值。"}
