如何从数据库ASP.NET中删除文件 [英] How do I delete files from database ASP.NET

问题描述

您好！我做了一个公文包，以便用户可以在那里存储文档。我使用一些教程制作了上传和删除方法，没关系，但是现在我必须制作一个删除方法而且我不知道如何。我尝试制作另一个gridview并生成删除方法，但varbinary（max）与sql_variant不兼容。这些是我上传或下载文件的方式。非常感谢！



我的尝试：



< pre lang =cs> protected void Page_Load（ object sender，EventArgs e）
{

if （！IsPostBack）
{
BindGrid（）;
}
}



private void BindGrid（）
{
string constr = ConfigurationManager.ConnectionStrings [ BazadedateConnectionString1]。ConnectionString;
使用（SqlConnection con = new SqlConnection（constr））
{
使用（SqlCommand cmd = new SqlCommand（））
{
cmd .CommandText = 从Servieta中选择ServietaID，Nume，其中FKuserID = @ FK;
cmd.Parameters.AddWithValue（ @ FK，user.Text）;
cmd.Connection = con;
con.Open（）;
GridView1.DataSource = cmd.ExecuteReader（）;
GridView1.DataBind（）;
con.Close（）;
}
}
}


受保护 void 上传（ object sender，EventArgs e）
{
string filename = Path.GetFileName（FileUpload1.PostedFile.FileName）;
string contentType = FileUpload1.PostedFile.ContentType;
使用（Stream fs = FileUpload1.PostedFile.InputStream）
{
使用（BinaryReader br = new BinaryReader（fs））
{
byte [] bytes = br.ReadBytes（（ Int32 ）fs.Length）;
string constr = ConfigurationManager.ConnectionStrings [ BazadedateConnectionString1\" ]的ConnectionString。
使用（SqlConnection con = new SqlConnection（constr））
{
string query = 插入Servieta值（@ Nume，@ Continut，@ Data，@ FKuserID）;
使用（SqlCommand cmd = new SqlCommand（query））
{
cmd.Connection = con;
cmd.Parameters.AddWithValue（ @ Nume，filename）;
cmd.Parameters.AddWithValue（ @ Continut，contentType）;
cmd.Parameters.AddWithValue（ @ Data，bytes）;
cmd.Parameters.AddWithValue（ @ FKuserID，Request.Cookies [ 登录] [ 用户ID]的ToString（））;
con.Open（）;
cmd.ExecuteNonQuery（）;
con.Close（）;
}
}
}
}
Response.Redirect（Request.Url.AbsoluteUri）;
}


受保护 void DownloadFile（< span class =code-keyword> object sender，EventArgs e）
{
// INT ID = int.Parse（（发送者作为LinkBut​​ton的）.CommandArgument）;
<跨度类= 代码关键字> INT ID = Convert.ToInt32（（ sender as LinkBut​​ton）.CommandArgument）;
byte [] bytes;
string fileName，contentType;
string constr = ConfigurationManager.ConnectionStrings [ BazadedateConnectionString1\" ]的ConnectionString。
使用（SqlConnection con = new SqlConnection（constr））
{
使用（SqlCommand cmd = new SqlCommand（））
{
cmd .CommandText = 从Servieta中选择Nume，Data，Continut，其中ServietaID = @ id;
cmd.Parameters.AddWithValue（ @ ID，id）;
cmd.Connection = con;
con.Open（）;
使用（SqlDataReader sdr = cmd.ExecuteReader（））
{
sdr.Read（）;
bytes =（ byte []）sdr [ 数据];
contentType = sdr [ Continut]。ToString（）;
fileName = sdr [ Nume]。ToString（）;
}





con.Close（）;
}
}
Response.Clear（）;
Response.Buffer = true ;
Response.Charset = ;
Response.Cache.SetCacheability（HttpCacheability.NoCache）;
Response.ContentType = contentType;
Response.AppendHeader（ Content-Disposition， attachment; filename = + fileName）;
Response.BinaryWrite（bytes）;
Response.Flush（）;
Response.End（）;
}

解决方案

我刚解决了这个问题。如果有人感兴趣，这些是代码。感谢您有兴趣帮助我！

 受保护  void  DeleteFile（ object  sender，EventArgs e）
 {
 
  int  id = Convert.ToInt32（（sender  as  LinkBut​​ton）.CommandArgument）; 
  string  connStr = ConfigurationManager.ConnectionStrings [  BazadedateConnectionString1\" ]的ConnectionString。 
  string  sqlStatement =  @ 从Servieta删除ServietaID = @ id; 
 使用（SqlConnection con =  new  SqlConnection（connStr））
 {
 使用（SqlCommand cmd =  new  SqlCommand（））
 {
 cmd .Connection = con; 
 cmd.CommandText = sqlStatement; 
 cmd.CommandType = CommandType.Text; 
 
 cmd.Parameters.AddWithValue（  @ ID，id）; 
 尝试 
 {
 con.Open（）; 
 cmd.ExecuteNonQuery（）; 
 BindGrid（）; 
} 
  catch （SqlException）
 {
 
} 
} 
 } 
 
} 

Hello! I made a briefcase so users can store documents there. I made the Upload and Delete methods using some tutorials, it's ok, but now i must made a delete method and I don't know how. I tried to make another gridview and generate delete method but "varbinary(max) is incompatible with sql_variant". These is how I upload or download files. Thank you very much !

What I have tried:

protected void Page_Load(object sender, EventArgs e)
        {

            if (!IsPostBack)
            {
                BindGrid();
            }
        }



        private void BindGrid()
        {
            string constr = ConfigurationManager.ConnectionStrings["BazadedateConnectionString1"].ConnectionString;
            using (SqlConnection con = new SqlConnection(constr))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.CommandText = "select ServietaID, Nume from Servieta where FKuserID=@FK";
                    cmd.Parameters.AddWithValue("@FK", user.Text);
                    cmd.Connection = con;
                    con.Open();
                    GridView1.DataSource = cmd.ExecuteReader();
                    GridView1.DataBind();
                    con.Close();
                }
            }
        }


        protected void Upload(object sender, EventArgs e)
        {
            string filename = Path.GetFileName(FileUpload1.PostedFile.FileName);
            string contentType = FileUpload1.PostedFile.ContentType;
            using (Stream fs = FileUpload1.PostedFile.InputStream)
            {
                using (BinaryReader br = new BinaryReader(fs))
                {
                    byte[] bytes = br.ReadBytes((Int32)fs.Length);
                    string constr = ConfigurationManager.ConnectionStrings["BazadedateConnectionString1"].ConnectionString;
                    using (SqlConnection con = new SqlConnection(constr))
                    {
                        string query = "insert into Servieta values (@Nume, @Continut, @Data, @FKuserID)";
                        using (SqlCommand cmd = new SqlCommand(query))
                        {
                            cmd.Connection = con;
                            cmd.Parameters.AddWithValue("@Nume", filename);
                            cmd.Parameters.AddWithValue("@Continut", contentType);
                            cmd.Parameters.AddWithValue("@Data", bytes);
                            cmd.Parameters.AddWithValue("@FKuserID", Request.Cookies["Login"]["userID"].ToString());
                            con.Open();
                            cmd.ExecuteNonQuery();
                            con.Close();
                        }
                    }
                }
            }
            Response.Redirect(Request.Url.AbsoluteUri);
        }


            protected void DownloadFile(object sender, EventArgs e)
            {
                //int id = int.Parse((sender as LinkButton).CommandArgument);
                int id = Convert.ToInt32((sender as LinkButton).CommandArgument);
                byte[] bytes;
                string fileName, contentType;
                string constr = ConfigurationManager.ConnectionStrings["BazadedateConnectionString1"].ConnectionString;
                using (SqlConnection con = new SqlConnection(constr))
                {
                    using (SqlCommand cmd = new SqlCommand())
                    {
                        cmd.CommandText = "select Nume, Data, Continut from Servieta where ServietaID=@id";
                        cmd.Parameters.AddWithValue("@ID", id);
                        cmd.Connection = con;
                        con.Open();
                        using (SqlDataReader sdr = cmd.ExecuteReader())
                        {
                            sdr.Read();
                            bytes = (byte[])sdr["Data"];
                            contentType = sdr["Continut"].ToString();
                            fileName = sdr["Nume"].ToString();
                        }





                        con.Close();
                    }
                }
                Response.Clear();
                Response.Buffer = true;
                Response.Charset = "";
                Response.Cache.SetCacheability(HttpCacheability.NoCache);
                Response.ContentType = contentType;
                Response.AppendHeader("Content-Disposition", "attachment; filename=" + fileName);
                Response.BinaryWrite(bytes);
                Response.Flush();
                Response.End();
            }

解决方案

I just solved the problem. These is the code if anyone is interested. Thank you for beeing interested to help me!

protected void DeleteFile(object sender, EventArgs e)
    {

        int id = Convert.ToInt32((sender as LinkButton).CommandArgument);
        string connStr = ConfigurationManager.ConnectionStrings["BazadedateConnectionString1"].ConnectionString;
        string sqlStatement = @"Delete from Servieta Where ServietaID=@id";
        using (SqlConnection con = new SqlConnection(connStr))
        {
            using (SqlCommand cmd = new SqlCommand())
            {
                cmd.Connection = con;
                cmd.CommandText = sqlStatement;
                cmd.CommandType = CommandType.Text;

                cmd.Parameters.AddWithValue("@ID", id);
                try
                {
                    con.Open();
                    cmd.ExecuteNonQuery();
                    BindGrid();
                }
                catch (SqlException)
                {

                }
            }
        }

    }

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