我是编码的新手，很抱歉，如果我的一些行话是错误的。
我正在尝试制作一个更新数据库值的更新页面。所有其他字段都更新正常，但每当我尝试在没有图像上载的情况下更新数据库时，它将使用空值替换当前字段值。任何帮助将不胜感激，以解决这个问题。确切的代码会非常好，正如我之前所说的那样，我对编码很感兴趣，特别是asp.net和C＃，所以有些术语对我来说是新的。
下面是我的代码隐藏文件，我想这是我问题的原因。
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;
using System.Data.SqlClient;
using System.Web.Configuration;
public partial class admin_updatenews : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void displayedit_ItemUpdated(object sender, ListViewUpdatedEventArgs e)
{
info.Text = "Item Updated";
FileUpload fileupdate = displayedit.EditItem.FindControl("imageupdate") as FileUpload;
Label recordid = displayedit.EditItem.FindControl("idlabel1") as Label;
Int32 id = Convert.ToInt32(recordid.Text);
if (fileupdate.HasFile)
{
String fupload = fileupdate.FileName;
Random r = new Random();
int rInt = r.Next(0, 10000);
String imgpath = "../images/" + rInt + fupload;
fileupdate.SaveAs(Server.MapPath(imgpath));
String newimage = rInt + fupload;
string newsconnection = WebConfigurationManager.ConnectionStrings["newsconnection"].ConnectionString;
SqlConnection myConnection = new SqlConnection(newsconnection);
//myConnection.ConnectionString is now set to connectionString.
myConnection.Open();
String query = "UPDATE News SET postimage ='" + newimage + "', Image ='" + newimage + "' WHERE id='" + id + "'";
SqlCommand myCommand = new SqlCommand(query, myConnection);
myCommand.ExecuteNonQuery();
myConnection.Close();
}
}
protected void displayedit_ItemEditing(object sender, ListViewEditEventArgs e)
{
info.Text = "I am editing";
}
protected void displayedit_ItemCanceling(object sender, ListViewCancelEventArgs e)
{
info.Text = "Not Updating";
}
}
如果需要，这是前端代码
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Copy of updatenews.aspx.cs" Inherits="admin_updatenews" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<link href="../css/responsive.css" rel='stylesheet' type='text/css' />
<link href="../css/gui.css" rel='stylesheet' type='text/css' />
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:SqlDataSource ID="newseditrows" runat="server"
ConnectionString='<%$ ConnectionStrings:newsconnection %>'
SelectCommand="SELECT News.id, News.headline, News.Image, News.paragraph, Sportslist.sportname, News.Sport, News.date, News.lead, News.authorID, Sportslist.id, News.postheadline, News.postimage, News.postparagraph, News.postsport, News.postdate, News.postlead, News.postauthorid
FROM News
INNER JOIN Sportslist ON News.Sport = Sportslist.id
ORDER BY News.id DESC"
UpdateCommand="UPDATE [News] SET [headline]=@headline, [Image]=@Image, [paragraph]=@paragraph, [Sport]=@sport, [date]=@date, [lead]=@lead, [authorid]=@authorid, [postheadline]=@headline, [postimage]=@Image, [postparagraph]=@paragraph, [postsport]=@sport, [postdate]=@date, [postlead]=@lead, [postauthorid]=@authorid WHERE [id]=@id">
<UpdateParameters>
<asp:Parameter Name="headline" Type="String" />
<asp:Parameter Name="Image" Type="String" />
<asp:Parameter Name="paragraph" Type="String" />
<asp:Parameter Name="Sport" Type="Int32" />
<asp:Parameter Name="date" Type="DateTime" />
<asp:Parameter Name="lead" Type="String" />
<asp:Parameter Name="authorid" Type="Int32" />
<asp:Parameter Name="id" Type="Int32" />
</UpdateParameters>
</asp:SqlDataSource>
<asp:SqlDataSource ID="sportlist" runat="server"
ConnectionString='<%$ ConnectionStrings:newsconnection %>'
SelectCommand="SELECT [id], [sportname] FROM [Sportslist]">
</asp:SqlDataSource>
<asp:Label ID="info" runat="server" Text="Not Updating"></asp:Label>
<br />
<asp:ListView ID="displayedit" runat="server"
DataSourceID="newseditrows"
DataKeyNames="id"
OnItemUpdated="displayedit_ItemUpdated"
OnItemEditing="displayedit_ItemEditing"
OnItemCanceling="displayedit_ItemCanceling">
<AlternatingItemTemplate>
<span style="">id:
<asp:Label Text='<%# Eval("id") %>' runat="server" ID="idLabel" /><br />
headline:
<asp:Label Text='<%# Eval("headline") %>' runat="server" ID="headlineLabel" /><br />
Image:
<asp:Image ID="ImageLabel" runat="server" ImageURL='<%# "../images/" + Eval("Image") %>' Width="100px" />
<br />
paragraph:
<asp:Label Text='<%# Eval("paragraph") %>' runat="server" ID="paragraphLabel" /><br />
Sport:
<asp:Label Text='<%# Eval("sportname") %>' runat="server" ID="SportLabel" /><br />
date:
<asp:Label Text='<%# Eval("date") %>' runat="server" ID="dateLabel" /><br />
lead:
<asp:Label Text='<%# Eval("lead") %>' runat="server" ID="leadLabel" /><br />
authorID:
<asp:Label Text='<%# Eval("authorID") %>' runat="server" ID="authorIDLabel" /><br />
<asp:Button runat="server" CommandName="Edit" Text="Edit" ID="EditButton" />
<br />
<br />
</span>
</AlternatingItemTemplate>
<EditItemTemplate>
<span style="">id:
<asp:Label Text='<%# Eval("id") %>' runat="server" ID="idLabel1" /><br />
headline:
<asp:TextBox Text='<%# Bind("headline") %>' runat="server" ID="headlineTextBox" /><br />
Image:
<asp:Image ID="ImageTextBox1" runat="server" ImageUrl='<%# "../images/" + Eval("Image") %>' Width="100px"/>
<asp:FileUpload ID="imageupdate" runat="server" />
<br />
paragraph:
<asp:TextBox Text='<%# Bind("paragraph") %>' runat="server" ID="paragraphTextBox" /><br />
Sport:
<%--<asp:TextBox Text='<%# Bind("Sport") %>' runat="server" ID="SportTextBox" />--%>
<asp:DropDownList ID="SportsDropdown" runat="server" SelectedValue='<%# Bind("Sport") %>'>
<asp:ListItem Value="1">Football</asp:ListItem>
<asp:ListItem Value="2">Rugby</asp:ListItem>
<asp:ListItem Value="3">Basketball</asp:ListItem>
<asp:ListItem Value="4">Motorsport</asp:ListItem>
<asp:ListItem Value="5">NFL</asp:ListItem>
<asp:ListItem Value="6">Cricket</asp:ListItem>
<asp:ListItem Value="7">Tennis</asp:ListItem>
<asp:ListItem Value="8">Golf</asp:ListItem>
<asp:ListItem Value="9">Other</asp:ListItem>
</asp:DropDownList>
<br />
lead:
<asp:TextBox Text='<%# Bind("lead") %>' runat="server" ID="leadTextBox" /><br />
<asp:Button runat="server" CommandName="Update" Text="Update" ID="UpdateButton" /><asp:Button runat="server" CommandName="Cancel" Text="Cancel" ID="CancelButton" /><br />
<br />
</span>
</EditItemTemplate>
<EmptyDataTemplate>
<span>No data was returned.</span>
</EmptyDataTemplate>
<InsertItemTemplate>
<span style="">headline:
<asp:TextBox Text='<%# Bind("headline") %>' runat="server" ID="headlineTextBox" /><br />
Image:
<asp:TextBox Text='<%# Bind("Image") %>' runat="server" ID="ImageTextBox" /><br />
paragraph:
<asp:TextBox Text='<%# Bind("paragraph") %>' runat="server" ID="paragraphTextBox" /><br />
Sport:
<asp:TextBox Text='<%# Bind("Sport") %>' runat="server" ID="SportTextBox" /><br />
date:
<asp:TextBox Text='<%# Bind("date") %>' runat="server" ID="dateTextBox" /><br />
lead:
<asp:TextBox Text='<%# Bind("lead") %>' runat="server" ID="leadTextBox" /><br />
authorID:
<asp:TextBox Text='<%# Bind("authorID") %>' runat="server" ID="authorIDTextBox" /><br />
<asp:Button runat="server" CommandName="Insert" Text="Insert" ID="InsertButton" /><asp:Button runat="server" CommandName="Cancel" Text="Clear" ID="CancelButton" /><br />
<br />
</span>
</InsertItemTemplate>
<ItemTemplate>
<span style="">id:
<asp:Label Text='<%# Eval("id") %>' runat="server" ID="idLabel" /><br />
headline:
<asp:Label Text='<%# Eval("headline") %>' runat="server" ID="headlineLabel" /><br />
Image:
<asp:Image ID="ImageLabel" runat="server" ImageURL='<%# "../images/" + Eval("Image") %>' Width="100px" />
<br />
paragraph:
<asp:Label Text='<%# Eval("paragraph") %>' runat="server" ID="paragraphLabel" /><br />
Sport:
<asp:Label Text='<%# Eval("sportname") %>' runat="server" ID="SportLabel" /><br />
date:
<asp:Label Text='<%# Eval("date") %>' runat="server" ID="dateLabel" /><br />
lead:
<asp:Label Text='<%# Eval("lead") %>' runat="server" ID="leadLabel" /><br />
authorID:
<asp:Label Text='<%# Eval("authorID") %>' runat="server" ID="authorIDLabel" /><br />
<asp:Button runat="server" CommandName="Edit" Text="Edit" ID="EditButton" />
<br />
<br />
</span>
</ItemTemplate>
<LayoutTemplate>
<div runat="server" id="itemPlaceholderContainer" style=""><span runat="server" id="itemPlaceholder" /></div>
<div style="">
<asp:DataPager runat="server" ID="DataPager1">
<Fields>
<asp:NextPreviousPagerField ButtonType="Button" ShowFirstPageButton="True" ShowNextPageButton="False" ShowPreviousPageButton="False"></asp:NextPreviousPagerField>
<asp:NumericPagerField></asp:NumericPagerField>
<asp:NextPreviousPagerField ButtonType="Button" ShowLastPageButton="True" ShowNextPageButton="False" ShowPreviousPageButton="False"></asp:NextPreviousPagerField>
</Fields>
</asp:DataPager>
</div>
</LayoutTemplate>
<SelectedItemTemplate>
<span style="">id:
<asp:Label Text='<%# Eval("id") %>' runat="server" ID="idLabel" /><br />
headline:
<asp:Label Text='<%# Eval("headline") %>' runat="server" ID="headlineLabel" /><br />
Image:
<asp:Label Text='<%# Eval("Image") %>' runat="server" ID="ImageLabel" /><br />
paragraph:
<asp:Label Text='<%# Eval("paragraph") %>' runat="server" ID="paragraphLabel" /><br />
Sport:
<asp:Label Text='<%# Eval("Sport") %>' runat="server" ID="SportLabel" /><br />
date:
<asp:Label Text='<%# Eval("date") %>' runat="server" ID="dateLabel" /><br />
lead:
<asp:Label Text='<%# Eval("lead") %>' runat="server" ID="leadLabel" /><br />
authorID:
<asp:Label Text='<%# Eval("authorID") %>' runat="server" ID="authorIDLabel" /><br />
<asp:Button runat="server" CommandName="Edit" Text="Edit" ID="EditButton" />
<br />
<br />
</span>
</SelectedItemTemplate>
</asp:ListView>
</div>
</form>
</body>
</html>
答案 0 :(得分：0)
以下是使用ur查询的更新语句示例。
UPDATE News
SET postimage = ISNULL(YourNewValue, postimage), Image = ISNULL(YourNewValue, Image)
WHERE id = YourID
编辑：
尝试在数据源updateCommand中添加以下内容。如果这不解决，请尝试单步执行以查看添加null的位置。
UpdateCommand="UPDATE [News] SET [headline]=@headline, [Image]= ISNULL(@Image, [Image]), [paragraph]=@paragraph, [Sport]=@sport, [date]=@date, [lead]=@lead, [authorid]=@authorid, [postheadline]=@headline, [postimage]=@Image, [postparagraph]=@paragraph, [postsport]=@sport, [postdate]=@date, [postlead]=@lead, [postauthorid]=@authorid WHERE [id]=@id">