c# - ExecuteNonQuery: Connection property has not been initialized.

Question

Afternoon, So I have been at this one issue for hours and can't really get past this last hump. Below is the code for this program that I am writing:

using System;  
using System.Collections.Generic;  
using System.Linq;  
using System.Text;  
using System.Diagnostics;  
using System.Data;  
using System.Data.SqlClient;  
using System.Configuration;  

namespace Test  
{  
  class Program  
  {  
    static void Main()  
    {  
      EventLog alog = new EventLog();  
      alog.Log = "Application";  
      alog.MachineName = ".";  
      foreach (EventLogEntry entry in alog.Entries)  
      {  
       SqlConnection connection1 = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=syslog2;Integrated Security=True");  
       SqlDataAdapter cmd = new SqlDataAdapter();  
       cmd.InsertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) ");  
       cmd.InsertCommand.Parameters.Add("@EventLog",SqlDbType.VarChar).Value = alog.Log;  
       cmd.InsertCommand.Parameters.Add("@TimeGenerated", SqlDbType.DateTime).Value = entry.TimeGenerated;  
       cmd.InsertCommand.Parameters.Add("@EventType", SqlDbType.VarChar).Value = entry.EntryType;  
       cmd.InsertCommand.Parameters.Add("@SourceName", SqlDbType.VarChar).Value = entry.Source;  
       cmd.InsertCommand.Parameters.Add("@ComputerName", SqlDbType.VarChar).Value = entry.MachineName;  
       cmd.InsertCommand.Parameters.Add("@InstanceId", SqlDbType.VarChar).Value = entry.InstanceId;  
       cmd.InsertCommand.Parameters.Add("@Message", SqlDbType.VarChar).Value = entry.Message;  
       connection1.Open();  
       cmd.InsertCommand.ExecuteNonQuery();  
       connection1.Close();  
      }   
    }  
  }  
}

The Code compiles fine without error or warning but when i go to run it, as soon as it gets to cmd.InsertCommand.ExecuteNonQuery(); I get the following error:

ExecuteNonQuery: Connection property has not been initialized.

Any ideas on what I missed?

score 43 · Accepted Answer

您需要将连接分配给SqlCommand，您可以使用构造函数或属性：

cmd.InsertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) ");
cmd.InsertCommand.Connection = connection1;

我强烈建议将using-statement用于实现IDisposablelike的任何类型SqlConnection，它也会关闭连接：

using(var connection1 = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=syslog2;Integrated Security=True"))
using(var cmd = new SqlDataAdapter())
using(var insertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) "))
{
    insertCommand.Connection = connection1;
    cmd.InsertCommand = insertCommand;
    //.....
    connection1.Open();
    // .... you don't need to close the connection explicitely
}

除此之外，您不需要DataAdapter为中的每个条目创建新连接foreach，即使创建、打开和关闭连接并不意味着ADO.NET 将创建、打开和关闭物理连接，而只是查看可用连接的连接池。然而，这是不必要的开销。

score 13 · Accepted Answer

您没有初始化连接。这就是为什么会出现这种错误的原因。

你的代码：

cmd.InsertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) ");

更正的代码：

cmd.InsertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) ",connection1);

score 1 · Accepted Answer

这里有几件事不对。

您真的要为每个日志条目打开和关闭连接吗？
你不应该使用SqlCommand而不是SqlDataAdapter吗？
数据适配器（或SqlCommand）需要的正是错误消息告诉您它丢失的内容：活动连接。仅仅因为您创建了一个连接对象并不会神奇地告诉 C# 它是您要使用的对象（尤其是在您尚未打开连接的情况下）。

我强烈推荐 C#/SQL Server 教程。

score 1 · Accepted Answer

实际上，当服务器建立连接但由于识别连接功能标识符失败而无法构建时会发生此错误。这个问题可以通过在代码中输入连接函数来解决。为此，我举一个简单的例子。在这种情况下，功能是 con 你可能会有所不同。

SqlCommand cmd = new SqlCommand("insert into ptb(pword,rpword) values(@a,@b)",con);

score 0 · Accepted Answer

打开和关闭连接需要很长时间。并按照另一位成员的建议使用“使用”。我稍微更改了您的代码，但将 SQL 创建和打开和关闭放在您的循环之外。这应该会加快执行速度。

  static void Main()
        {
            EventLog alog = new EventLog();
            alog.Log = "Application";
            alog.MachineName = ".";
            /*  ALSO: USE the USING Statement as another member suggested
            using (SqlConnection connection1 = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=syslog2;Integrated Security=True")
            {

                using (SqlCommand comm = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) ", connection1))
                {
                    // add the code in here
                    // AND REMEMBER: connection1.Open();

                }
            }*/
            SqlConnection connection1 = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=syslog2;Integrated Security=True");
            SqlDataAdapter cmd = new SqlDataAdapter();
            // Do it one line
            cmd.InsertCommand = new SqlCommand("INSERT INTO Application VALUES (@EventLog, @TimeGenerated, @EventType, @SourceName, @ComputerName, @InstanceId, @Message) ", connection1);
            // OR YOU CAN DO IN SEPARATE LINE :
            // cmd.InsertCommand.Connection = connection1;
            connection1.Open();

            // CREATE YOUR SQLCONNECTION ETC OUTSIDE YOUR FOREACH LOOP
            foreach (EventLogEntry entry in alog.Entries)
            {
                cmd.InsertCommand.Parameters.Add("@EventLog", SqlDbType.VarChar).Value = alog.Log;
                cmd.InsertCommand.Parameters.Add("@TimeGenerated", SqlDbType.DateTime).Value = entry.TimeGenerated;
                cmd.InsertCommand.Parameters.Add("@EventType", SqlDbType.VarChar).Value = entry.EntryType;
                cmd.InsertCommand.Parameters.Add("@SourceName", SqlDbType.VarChar).Value = entry.Source;
                cmd.InsertCommand.Parameters.Add("@ComputerName", SqlDbType.VarChar).Value = entry.MachineName;
                cmd.InsertCommand.Parameters.Add("@InstanceId", SqlDbType.VarChar).Value = entry.InstanceId;
                cmd.InsertCommand.Parameters.Add("@Message", SqlDbType.VarChar).Value = entry.Message;
                int rowsAffected = cmd.InsertCommand.ExecuteNonQuery();
            }
            connection1.Close(); // AND CLOSE IT ONCE, AFTER THE LOOP
        }

score -1 · Accepted Answer

试试这个..

您需要在执行之前connection.open()在SqlCommand.Connection对象上使用打开连接ExecuteNonQuery()

score -1 · Accepted Answer

双击您的表单以创建 form_load 事件。然后在该事件中写入 command.connection = "your connection name";

c# - ExecuteNonQuery: Connection property has not been initialized.

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