string sqldatabase = string.Format(dr["sql"].ToString(), drpat["PATIENT_ID"].ToString());
                        string tablename = dr["SQL_NAME"].ToString();
                        DataTable dtdatabasedata = http://www.mamicode.com/new >                        dtdatabasedata = http://www.mamicode.com/DALUse.Query(sqldatabase).Tables[0];
                        dtdatabasedata.TableName = tablename;
                        exportdata.Tables.Add(dtdatabasedata.Copy());

DataTable的名称要后设置，否则就是默认的ds了。

ps:Copy()方法会把tablename也复制过去。