Question

我收到以下错误：

System.Data.dll中出现未处理的“System.InvalidOperationException”类型异常

其他信息：超时已过期。从池中获取连接之前经过的超时时间。这可能是因为所有池连接都在使用中并且达到了最大池大小。

这是我尝试使用计时器每秒从数据库读取一个值。

以下是代码。我知道这是因为SQL连接没有关闭。但是我可以做些什么来解决它？

  public void showcount2(int ID)
        {
            notifyIcon1.Visible = true;
            string count;
            string connString = ConfigurationManager.ConnectionStrings["Dbconn"].ToString();
            SqlConnection connection = new SqlConnection(connString); // defining sql connection
            connection.Open(); // opening connection
            SqlCommand cmd1 = connection.CreateCommand();
            cmd1.CommandText = "select count from dbo.tblcount where UserID = " + ID;
            DataSet datasetFBK1 = new DataSet();
            SqlDataAdapter dataadapterFBK1 = new SqlDataAdapter(cmd1);
            dataadapterFBK1.Fill(datasetFBK1);
            SqlDataReader dr1 = cmd1.ExecuteReader();
            if (dr1.Read())
            {
                string countcheck;
                countcheck = notifyIcon2.Text;
                count = dr1[0].ToString();
                notifyIcon2.Text = "NCT COUNT FOR COLLEAGUE IS: " + count;
                if (countcheck == notifyIcon2.Text)
                {
                    return;
                }
                else
                {
                    notifyIcon2.BalloonTipText = "NCT COUNT FOR COLLEAGUE IS: " + count;
                    notifyIcon2.ShowBalloonTip(50000);
                }

                //pick a colored icon based on the count of the NCT cases
                if (Convert.ToInt32(count) <= 3)
                {
                    notifyIcon2.Icon = new Icon("C:\\BackupFromPC\\greenicon.ico");
                }
                else if (Convert.ToInt32(count) > 3 && Convert.ToInt32(count) <= 5)
                {
                    notifyIcon2.Icon = new Icon("C:\\BackupFromPC\\yellowicon.ico");

                }
                else if (Convert.ToInt32(count) > 5)
                {
                    notifyIcon2.Icon = new Icon("C:\\BackupFromPC\\redicon.ico");
                }
                //------------------------------
                connection.Close();
            }

        }

Answer 1

我知道，因为SQL连接没有关闭。但是我可以做些什么来解决它？

好吧，关闭它。最简单的方法是将连接的使用括在using块中：

using(SqlConnection connection = new SqlConnection(connString))
{
    // the rest of your code goes here
}

using语句转换为try/finally块。在finally块中（当return或以其他方式离开范围时将始终执行）connection将自动关闭。

Answer 2

你应该使用:-) 您退出示波器时将处理您使用的所有内容。包括关闭SqlConnections

像这样：

    using (SqlConnection connection = new SqlConnection(connString))
    {
        using (SqlDataReader dr1 = cmd1.ExecuteReader())
        {
            if (dr1.Read())
            {
                string countcheck;
                countcheck = notifyIcon2.Text;
                count = dr1[0].ToString();
                notifyIcon2.Text = "NCT COUNT FOR COLLEAGUE IS: " + count;
                if (countcheck == notifyIcon2.Text)
                {
                    return;
                }
                else
                {
                    notifyIcon2.BalloonTipText = "NCT COUNT FOR COLLEAGUE IS: " + count;
                    notifyIcon2.ShowBalloonTip(50000);
                }

                //pick a colored icon based on the count of the NCT cases
                if (Convert.ToInt32(count) <= 3)
                {
                    notifyIcon2.Icon = new Icon("C:\\BackupFromPC\\greenicon.ico");
                }
                else if (Convert.ToInt32(count) > 3 && Convert.ToInt32(count) <= 5)
                {
                    notifyIcon2.Icon = new Icon("C:\\BackupFromPC\\yellowicon.ico");

                }
                else if (Convert.ToInt32(count) > 5)
                {
                    notifyIcon2.Icon = new Icon("C:\\BackupFromPC\\redicon.ico");
                }
                //------------------------------                
            }
        }
    }

超时过期错误：在循环中使用DataReader时

2 个答案: