编号自动增长

                Dbhelp myDbhelp = new Dbhelp();
                OracleConnection myOracleConnection = myDbhelp.getConnection();
                myDbhelp.open();
                string str = "select concat('E',substr(concat('00000000',COALESCE(to_char(to_number(max(to_number('00000000'||ltrim(AS_EQUIPMENTID,'E'))))+1),'1')),-8)) str from AS_ASSETS";//编号自动增长
                OracleCommand cmd = new OracleCommand(str, myOracleConnection);
                string id = cmd.ExecuteScalar().ToString();
                return id;