使用查询字符串和名称从数据库中删除文件

我正在尝试为用户创建一个删除页面，以删除相册中的选定图像文件。我只是不知道如何使用 url 查询字符串选择数据库表行"navn"（英语中的"name"）。

我应该为此行创建一个新的 SqlConnection 和 select命令吗？

我不太确定该怎么做，因为我刚刚开始学习 ASP.NET、C# 和 SQL 的基础知识。

（我希望丹麦语条目不会太混乱。欢迎你问，如果有什么不合理的话。

我想也许我应该在Request.QueryString之后放一些东西来选择表中的"navn"行。

File.Delete(Server.MapPath("~/upload/originals/" + 
            Request.QueryString["id"].ToString()));

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db表"billeder"（英文"images"）：

• ID [int]
• imgnavn [Nvarchar]
• 拇指导航 [Nvarchar]
• alt [Nvarchar]
• oprettetDen（创建日期） [日期时间]
• redigeretDen（最后更改） [日期时间]

---

下面是 aspx 页和代码隐藏文件的完整代码：

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（"sletBtn"是"删除按钮"）

sletBilleder.aspx

<%@ Page Title="" Language="C#" MasterPageFile="~/admin/AdminMasterPage.master" AutoEventWireup="true" CodeFile="SletBilleder.aspx.cs" Inherits="admin_SletBilleder" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head2" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder3" Runat="Server">
    <table>   
        <tr>
            <th>
                <label>Billede-ID</label>
            </th>
            <th>
                <label>Billede-navn</label>
            </th>
        </tr>
        <tr>
            <td>
                <asp:Label ID="billedeID" runat="server"></asp:Label>
            </td>
            <td>
                <asp:Label ID="billedenavn" runat="server"></asp:Label>
            </td>
        </tr>
    </table>
    <asp:Label ID="Label_msg" runat="server"></asp:Label>
    <asp:Button ID="sletBtn" runat="server" Text="Slet billedet" 
                OnClick="sletBtn_Click" />
    <asp:Button ID="tilAlbumBtn" runat="server" Text="Gå tilbage" 
                OnClick="tilAlbumBtn_Click" />
</asp:Content>

---

sletBilleder.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Data.SqlClient;
using System.Configuration;
using System.Data;
public partial class admin_SletBilleder : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            Label_msg.Text = "<div class='span6 offset1'><div class='alert alert-success'>Er du sikker på, at du vil slette billedet</div></div>";
        }
        // opret forbindelse til databasen
        SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString());
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = conn;
        // SQL strengen
        cmd.CommandText = "SELECT * FROM [billeder] WHERE [Id] = @Id";
        cmd.Parameters.Add("@Id", SqlDbType.Int).Value = Request.QueryString["id"];
        //åben for forbindelsen til databasen
        conn.Open();
        SqlDataReader reader = cmd.ExecuteReader();
        if (reader.Read())
        {
            billedeID.Text = reader["Id"].ToString();
            billedenavn.Text = reader["imgnavn"].ToString();
        }
        // Luk for forbindelsen til databasen
        // reader.Close();
        conn.Close();
    }
    protected void sletBtn_Click(object sender, EventArgs e)
    {
        try
        {
            // slet Originalfilen i image/upload/Original/ mappen
            File.Delete(Server.MapPath("~/upload/originals/" + Request.QueryString["id"].ToString()));
            // Slet Thumbsfilen i /Images/Upload/Thumbs/
            File.Delete(Server.MapPath("~/upload/thumbs/" + Request.QueryString["id"].ToString()));
            // Slet Resized_Original i /Images/Upload/Resized_Original/ mappen
            File.Delete(Server.MapPath("~/upload/originalsResized/" + Request.QueryString["id"].ToString()));
            // slet filen i databasen
            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString());
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandText = "DELETE FROM Billeder WHERE Id = @ImageId";
            cmd.Parameters.Add("@ImageId", SqlDbType.Int).Value = Request.QueryString["id"].ToString();
            conn.Open();
            cmd.ExecuteNonQuery();
            conn.Close();
            //Redirect til Galleri
            Response.Redirect("default.aspx");
        }
        catch (Exception)
        {
            Label_msg.Text = "<div class='span6 offset1'><div class='alert alert-success'>Billedet blev desværre <b>ikke</b> slettet</div></div>";
        }
    }
    protected void tilAlbumBtn_Click(object sender, EventArgs e)
    {
        Response.Redirect("visBilleder.aspx?id=" + Request.QueryString["id"]);
    }
}

protected void Page_Load(object sender, EventArgs e)
{
    ....
    if (reader.Read())
    {
        billedeID.Text = reader["Id"].ToString();
        billedenavn.Text = reader["imgnavn"].ToString();
        ViewState["imgnavn"] = reader["imgnavn"].ToString();
    }
    ....
}
protected void sletBtn_Click(object sender, EventArgs e)
{
    try
    {
        string imageName = ViewState["imgnavn"].ToString();    
        // slet Originalfilen i image/upload/Original/ mappen
        File.Delete(Server.MapPath("~/upload/originals/" + imageName));
        // Slet Thumbsfilen i /Images/Upload/Thumbs/
        File.Delete(Server.MapPath("~/upload/thumbs/" + imageName));
        // Slet Resized_Original i /Images/Upload/Resized_Original/ mappen
        File.Delete(Server.MapPath("~/upload/originalsResized/" + imageName));
        ...
    }
    ...
}

File.Delete(Server.MapPath("~/upload/originals/" + Request.QueryString["id"].ToString()));

File.Delete(Server.MapPath("~/upload/originals/") + Request.QueryString["id"].ToString());

string path = Server.MapPath("~/upload/originals/") + Request.QueryString["id"].ToString();