ExecuteNonQuery:连接属性尚未初始化. [英] ExecuteNonQuery: Connection property has not been initialized.

问题描述

下午，所以我已经在这个问题上呆了几个小时，无法真正克服这最后的难关.下面是我正在编写的这个程序的代码:

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();  
      }   
    }  
  }  
} 

代码编译得很好，没有错误或警告，但是当我运行它时，只要它到达 cmd.InsertCommand.ExecuteNonQuery();我收到以下错误:

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:连接属性尚未初始化.

ExecuteNonQuery: Connection property has not been initialized.

对我错过的东西有什么想法吗?

Any ideas on what I missed?

推荐答案

需要将连接分配给SqlCommand，可以使用构造函数 或 属性:

You need to assign the connection to the SqlCommand, you can use the constructor or the property:

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

我强烈建议使用 using-statement 对于任何实现 IDisposable 的类型，比如 SqlConnection，它也会关闭连接:

I strongly recommend to use the using-statement for any type implementing IDisposable like SqlConnection, it'll also close the connection:

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，您不需要为 foreach 中的每个条目创建新的连接和 DataAdapter，即使创建、打开和关闭连接确实not 意味着 ADO.NET 将创建、打开和关闭物理连接，而只是查看 connection-pool 用于可用连接.然而，这是不必要的开销.

Apart from that you don't need to create a new connection and DataAdapter for every entry in the foreach, even if creating, opening and closing a connection does not mean that ADO.NET will create, open and close a physical connection but just looks into the connection-pool for an available connection. Nevertheless it's an unnecessary overhead.

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