C＃SqlDataReader被关闭

Opelhatza

我不知道为什么我会例外。它说读者在我尝试访问它之前已关闭。为什么会这样？

这是代码：

//Load Projects from SQL Server (nothing else)
public SPpowerPlantList loadProjectsFromServer(DateTime timestamp, string note, string sqlServer, string database)
{
    SqlConnection sqlConnection = new SqlConnection(String.Format(@"Integrated Security=SSPI;server={0};Initial Catalog={1};", sqlServer, database));
    sqlConnection.Open();

    string selectstring = "SELECT * FROM [dbo].[tblSPpowerPlant]"; //(WHERE note {0} = " + note + " AND timestamp {1} = " + timestamp;
        SqlCommand sqlSelectCommand = new SqlCommand(selectstring, sqlConnection);
    sqlSelectCommand.CommandType = CommandType.Text;
    sqlSelectCommand.CommandText = selectstring;

    SqlDataReader reader;

    SPpowerPlantList powerPlantList = new SPpowerPlantList();

    reader = sqlSelectCommand.ExecuteReader();

    //this line trowhs the exeption
    while (reader.Read())
    {
        foreach (SPpowerPlant powerPlant in powerPlantList)
        {
            powerPlant.ID = reader.GetInt32(0);
            powerPlant.projectName = reader.GetString(1).ToString();
            powerPlant.location = reader.GetString(2); 
            powerPlant.shortName = reader.GetString(3); 
            powerPlant.numberOfWtgs = reader.GetInt32(4); 
            powerPlant.mwWtg = reader.GetDouble(5); 
            powerPlant.mwTotal = reader.GetDouble(6); 
            powerPlant.projectShareWeb = reader.GetDouble(7); 
            powerPlant.mwWeb = reader.GetDouble(8); 
            powerPlant.phase = reader.GetString(9); 
            powerPlant.phaseNumber = reader.GetString(10);
            powerPlant.phaseDescription = reader.GetString(11); 
            powerPlant.projectProgress = reader.GetDouble(12); 
            powerPlant.mwDeveloped = reader.GetDouble(13); 
            powerPlant.projectManager = reader.GetString(14); 
            powerPlant.spaceUrl = reader.GetString(15); 
            powerPlant.country = reader.GetString(16); 
            powerPlant.technology = reader.GetString(17);
            powerPlant.state = reader.GetString(18);
            powerPlant.allPermits = reader.GetDateTime(19);
            powerPlant.cod = reader.GetDateTime(20);
            powerPlant.stateSince = reader.GetDateTime(21);
            powerPlant.spID = reader.GetInt32(22);
            powerPlant.currency = reader.GetString(23);
            powerPlant.possibleWtgTypes = reader.GetString(24);
            powerPlant.hubHeight = reader.GetString(25);
            powerPlant.visibility = reader.GetString(26);
            powerPlant.templateName = reader.GetString(27);

            powerPlantList.Add(powerPlant);
        }

        reader.Dispose();
        sqlConnection.Close(); 
    }

    return powerPlantList;
}

这是例外情况（谷歌翻译）：

尝试读取无效，因为数据读取器已关闭。

我尝试了谷歌，但没有运气。因此，任何帮助都会很棒。谢谢你的时间。

顺便说一句，抱歉我的英语不是我的母语，但我正在努力。

佐哈尔·皮莱德（Zohar Peled）

代码行

reader.Dispose();
sqlConnection.Close();

在while(reader.read())循环内。

另外，最好使用using而不是Dispose()自欺欺人。

public SPpowerPlantList loadProjectsFromServer(DateTime timestamp, string note, string sqlServer, string database)
{
    using(var sqlConnection = new SqlConnection(String.Format(@"Integrated Security=SSPI;server={0};Initial Catalog={1};", sqlServer, database)))
    {
        sqlConnection.Open();

        var selectstring = "SELECT * FROM [dbo].[tblSPpowerPlant]"; //(WHERE note {0} = " + note + " AND timestamp {1} = " + timestamp;
        var sqlSelectCommand = new SqlCommand(selectstring, sqlConnection);
        sqlSelectCommand.CommandType = CommandType.Text;
        sqlSelectCommand.CommandText = selectstring;

        SPpowerPlantList powerPlantList = new SPpowerPlantList();

        using(var reader = sqlSelectCommand.ExecuteReader())
        {
            while (reader.Read())
            {
                foreach (SPpowerPlant powerPlant in powerPlantList)
                {
                    powerPlant.ID = reader.GetInt32(0);
                    powerPlant.projectName = reader.GetString(1).ToString();
                    powerPlant.location = reader.GetString(2); 
                    powerPlant.shortName = reader.GetString(3); 
                    powerPlant.numberOfWtgs = reader.GetInt32(4); 
                    powerPlant.mwWtg = reader.GetDouble(5); 
                    powerPlant.mwTotal = reader.GetDouble(6); 
                    powerPlant.projectShareWeb = reader.GetDouble(7); 
                    powerPlant.mwWeb = reader.GetDouble(8); 
                    powerPlant.phase = reader.GetString(9); 
                    powerPlant.phaseNumber = reader.GetString(10);
                    powerPlant.phaseDescription = reader.GetString(11); 
                    powerPlant.projectProgress = reader.GetDouble(12); 
                    powerPlant.mwDeveloped = reader.GetDouble(13); 
                    powerPlant.projectManager = reader.GetString(14); 
                    powerPlant.spaceUrl = reader.GetString(15); 
                    powerPlant.country = reader.GetString(16); 
                    powerPlant.technology = reader.GetString(17);
                    powerPlant.state = reader.GetString(18);
                    powerPlant.allPermits = reader.GetDateTime(19);
                    powerPlant.cod = reader.GetDateTime(20);
                    powerPlant.stateSince = reader.GetDateTime(21);
                    powerPlant.spID = reader.GetInt32(22);
                    powerPlant.currency = reader.GetString(23);
                    powerPlant.possibleWtgTypes = reader.GetString(24);
                    powerPlant.hubHeight = reader.GetString(25);
                    powerPlant.visibility = reader.GetString(26);
                    powerPlant.templateName = reader.GetString(27);

                    powerPlantList.Add(powerPlant);
                }
            }
        }           

    }
    return powerPlantList;
}

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