C＃的WinForms Npgsql 3.0.5"正在进行&QUOT的操作;试图运行相同的连接中的多个命令时出错 [英] C# Winforms Npgsql 3.0.5 "An operation already in progress" error when trying to run multiple commands inside same connection

问题描述

我试图运行在C＃中的WinForms下面的代码片段。这段代码与pgsql的2.2.6适配器运作良好。什么修正可以以做工精细用pgsql3.0.5适配器进行？谢谢

I'm trying to run the following snippet in C# Winforms. This piece of code is working well with pgsql 2.2.6 adapter. What correction can be made in order to work fine with pgsql3.0.5 adapter? Thanks.

NpgsqlConnection conn = new NpgsqlConnection(MainForm2.MyConString);
        {
            conn.Open();
            using (NpgsqlCommand cmd = new NpgsqlCommand("SELECT rfid,name,sc_id from passenger ORDER by name", conn))
            {
                NpgsqlDataReader dr = cmd.ExecuteReader();
                while (dr.Read())
                {
                    var obj = new PassengerClass
                    {
                        RFID = dr.GetString(0),
                        Name = dr.GetString(1),
                        sc_id = dr.GetInt32(2)
                    };
                    s = dr.GetString(0);
                    try { ret.Add(s, obj); }
                    catch (Exception ex) { SM.Debug("Fail to add RFID Name in hash RFID:" + s + ex.ToString()); }
                }
            }
            MainForm2.PassHash = ret;
            try
            {
                using (NpgsqlCommand cmd = new NpgsqlCommand(string.Format("UPDATE place set useridx ={0} where useridx=0", MainForm2.userIDX), conn))
                    cmd.ExecuteNonQuery();

                using (NpgsqlCommand cmd = new NpgsqlCommand(string.Format("UPDATE zonename set useridx ={0} where useridx=0", MainForm2.userIDX), conn))
                    cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                SM.Debug("Error on update users IDX for place and zone with value 0 :" + ex.ToString());
            }

因此，在第二个命令语句它给了我以下错误：

So, at the second command statement it gives me the following error:

型的第一个机会异常'System.InvalidOperationException'
发生在Npgsql.dll

A first chance exception of type 'System.InvalidOperationException' occurred in Npgsql.dll

更多信息：操作已在进行中。

Additional information: An operation is already in progress.

的

修改其他信息：
的

推荐答案

您需要处置其在第一个的ExecuteReader调用得到NpgsqlDataReader，用using语句包住它，就像你与你的NpgsqlCommand做的。

You need to dispose of the NpgsqlDataReader which you get in the first ExecuteReader call, wrap it with a using statement just like you do with your NpgsqlCommand.

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