下面是一个ASP.NET MVC核心操作：

public ActionResult<object> Try()
    OracleConnection conn = (OracleConnection)_context.Database.GetDbConnection();
    if (conn.State != ConnectionState.Open)
        conn.Open();
    var cmd = conn.CreateCommand();
    cmd.CommandText = "select * from mytable fetch first 1 rows only";
    var result = new List<string>();
    using (OracleDataReader reader = cmd.ExecuteReader())
        while (reader.Read())
            result.Add(reader.GetName(0)+": "+reader.GetValue(0).ToString());
    return string.Join(',',result);
}

然后执行以下操作：

1创建和填写表：

create table mytable (f1 number(10), f2 varchar2(10));
insert into mytable values (32,'32');
grant select on mytable to myuser;

2呼吁行动：

http://localhost/MyController/Try
// output is okay:
// F1: 32

3然后：

alter table mytable add f3 varchar2(5) default ('f3') null;

4再次呼吁采取行动：

http://localhost/MyController/Try

这会在OracleCommand.ExecuteReader中引发异常：

System.Exception
  HResult=0x80131500
  Message=Internal Error