ExecuteNonQuery：连接属性尚未初始化？

Question

我的代码中有错误：

ExecuteNonQuery：连接属性尚未初始化。

这可能是由于此代码中的行：

OdbcCommand cmd = new OdbcCommand("INSERT INTO Pictures (UserID, picturepath) VALUES ('" + theUserId + "' , '" + fileuploadpath + "')");

完整代码：

{
    string theUserId = Session["UserID"].ToString();
    {
        OdbcConnection cn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; Server=localhost; Database=gymwebsite2; User=root; Password=commando;");
        cn.Open();
    }
    if (FileUploadControl.HasFile)
    {
        try
        {
            string filename = Path.GetFileName(FileUploadControl.FileName);
            //FileUploadControl.SaveAs(Server.MapPath("~/userdata/" + theUserId + "/uploadedimage/") + filename);
            string fileuploadpath = Server.MapPath("~/userdata/" + theUserId + "/uploadedimage/");
            FileUploadControl.SaveAs(Path.Combine(fileuploadpath, filename));
            StatusLabel.Text = "Upload status: File uploaded!";



            OdbcCommand cmd = new OdbcCommand("INSERT INTO Pictures (UserID, picturepath) VALUES ('" + theUserId + "' , '" + fileuploadpath + "')");
            cmd.ExecuteNonQuery();
        }

        catch (Exception ex)
        {
            StatusLabel.Text = "Upload status: The file could not be uploaded. The following error occured: " + ex.Message;

        }

    }
}

        }

还有一个问题，我不认为它是我想要的插入，因为这会在我的数据库中创建重复条目，是否只是将其从 INSERT INTO 更改为 UPDATE 的情况？

还有没有办法在上传图片时覆盖？自动取款机只是将图像保存到与我已有的文件夹相同的文件夹中吗？第一张图像或任何图像显然不会具有相同的文件名，那么我将如何用我上传的那个覆盖文件夹中的任何图像？

编辑：

新错误（fileupload 工作正常，因为它存储在正确的区域，但将 fileupload 传递给 insert 语句有点不靠谱）

我得到了错误

无法上传文件。发生以下错误：ERROR [42000] [MySQL][ODBC 3.51 Driver][mysqld-5.5.9]您的 SQL 语法有错误；检查与您的 MySQL 服务器版本相对应的手册，以在第 1 行的 ''C:\Users\Garrith\Documents\Visual Studio 2010\WebSites\WebSite1\userdata\1\uplo' 附近使用正确的语法

这有什么奇怪的？

我想要做的就是将文件路径+文件名保存在 mydb 中，我试图传递给插入的尝试显然失败了。

protected void UploadButton_Click(object sender, EventArgs e)
{
    if (FileUploadControl.HasFile)
    {
        try
        {
            string theUserId = Session["UserID"].ToString();
            OdbcConnection cn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; Server=localhost; Database=gymwebsite2; User=root; Password=commando;");
            cn.Open();
            string filename = Path.GetFileName(FileUploadControl.FileName);
            //FileUploadControl.SaveAs(Server.MapPath("~/userdata/" + theUserId + "/uploadedimage/") + filename);
            string fileuploadpath = Server.MapPath("~/userdata/" + theUserId + "/uploadedimage/");
            FileUploadControl.SaveAs(Path.Combine(fileuploadpath, filename));
            StatusLabel.Text = "Upload status: File uploaded!";
            //some kind of function to take the path then enter it into my insert syntax?
            OdbcCommand cmd = new OdbcCommand("INSERT INTO Pictures (UserID, picturepath) VALUES ('" + theUserId + "' , '" + fileuploadpath + "')", cn);
            cmd.ExecuteNonQuery();
        }
        catch (Exception ex)
        {
            StatusLabel.Text = "Upload status: The file could not be uploaded. The following error occured: " + ex.Message;
        }
    }
}
        }

正如你在这一行看到的：

VALUES ('" + theUserId + "' , '" + fileuploadpath + "')", cn);

我错过了“文件名”我试过这个：

VALUES ('" + theUserId + "' , '" + fileuploadpath, filename + "')", cn);

便宜的镜头哈哈，但我想值得一试，它像往常一样哭泣！

Answer 1

以下在语法上是fubar'd：

string theUserId = Session["UserID"].ToString();
{
    OdbcConnection cn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; Server=localhost; Database=gymwebsite2; User=root; Password=commando;");
    cn.Open();
}

Answer 2

你需要把连接和cmd关联起来：

OdbcCommand cmd = 
  new OdbcCommand("INSERT INTO Pictures (UserID, picturepath) VALUES ('" + theUserId + "' , '" + fileuploadpath + "')");       

cmd.Connection = cn;  // <--------

cmd.ExecuteNonQuery();

另外，去掉这里的大括号：

{         
    OdbcConnection cn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; 
    Server=localhost; Database=gymwebsite2; User=root; Password=commando;");          cn.Open(); 
} 

Answer 3

您想在OdbcConnection 上使用CreateCommand 创建OdbcCommand。发布的代码不会将cmd 绑定到cn。此外，您应该使用 CommandParameters 而不是内联值（以防止 SQL 注入攻击）。

OdbcCommand cmd = cn.CreateCommand();
cmd.CommandText = "INSERT INTO Pictures (UserID, picturepath) VALUES (?, ?)";
cmd.Parameters.Add(new OdbcParameter("@UserID", OdbcType.Int, theUserID));
cmd.Parameters.Add(new OdbcParameter("@picturepath", OdbcType.VarChar, fileuploadpath));
cmd.ExecuteNonQuery();

Answer 4

这就是问题所在：

OdbcCommand cmd = new OdbcCommand("INSERT INTO Pictures (UserID, picturepath) VALUES ('" + theUserId + "' , '" + fileuploadpath + "')");  <--- there is no connection intialize here

改成：

    //eg: odbconnection cn = new odbcconnection();

string fileup = fileupload + "," filename;


    OdbcCommand cmd = new OdbcCommand("INSERT INTO Pictures (UserID, picturepath) VALUES ('" + theUserId + "' , '" + fileup.ToString() + "')",cn);  

问候