我正在尝试制作一个简单的图书馆数据库。我在 gridview 中列出搜索结果，然后我有一个文本框和一个按钮，用户输入 isbn 并单击贷款按钮。然后，如果有足够数量的项目（itemNumber>0），则由用户借出。这是用户界面的屏幕截图：
我的问题是，当用户点击贷款按钮时，贷款可能成功也可能不成功。在这两种情况下，我都会打印一条消息，指示贷款是否成功，并且我还希望显示更新的网格视图。问题是，按下贷款按钮后，gridview 消失了，我只看到屏幕上的文本框、按钮和消息。按下贷款按钮后如何显示gridview的更新版本？
这是代码文件：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="SearchResults.aspx.cs" Inherits="Pages_SearchResults" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
</div>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataKeyNames="ISBN" DataSourceID="SqlDataSource1"
onselectedindexchanged="GridView1_SelectedIndexChanged"
onrowcommand="GridView1_RowCommand">
<Columns>
<asp:BoundField DataField="Title" HeaderText="Title" SortExpression="Title" />
<asp:BoundField DataField="ISBN" HeaderText="ISBN" ReadOnly="True"
SortExpression="ISBN" />
<asp:BoundField DataField="AuthorName" HeaderText="AuthorName"
SortExpression="AuthorName" />
<asp:BoundField DataField="AuthorlName" HeaderText="AuthorlName"
SortExpression="AuthorlName" />
<asp:BoundField DataField="ItemType" HeaderText="ItemType"
SortExpression="ItemType" />
<asp:BoundField DataField="PublishYear" HeaderText="PublishYear"
SortExpression="PublishYear" />
<asp:BoundField DataField="numOfCopies" HeaderText="Number of Copies"
SortExpression="numOfCopies" />
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
SelectCommand="SELECT * FROM [Items] WHERE ([Title] LIKE '%' + @Title + '%')">
<SelectParameters>
<asp:FormParameter FormField="tSearchBox" Name="Title" Type="String" />
</SelectParameters>
</asp:SqlDataSource>
<br />
<asp:Label ID="Label1" runat="server" Text="Type ISBN to loan:"></asp:Label>
这是 .cs 文件：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
public partial class Pages_SearchResults : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
Response.Redirect("Default.aspx");
}
protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
SqlConnection con = new SqlConnection();
con.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=D:\\Users\\SUUSER\\Documents\\Visual Studio 2010\\Projects\\Library\\LibWebSite\\App_Data\\LibDatabase.mdf;Integrated Security=True;User Instance=True";
Int32 verify;
string title = GridView1.HeaderRow.Cells[0].Text, isbn = GridView1.HeaderRow.Cells[1].Text, name = GridView1.HeaderRow.Cells[2].Text, lname = GridView1.HeaderRow.Cells[3].Text, type = GridView1.HeaderRow.Cells[4].Text, year = GridView1.HeaderRow.Cells[5].Text;
}
protected void bLoanButton_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection();
con.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=D:\\Users\\SUUSER\\Documents\\Visual Studio 2010\\Projects\\Library\\LibWebSite\\App_Data\\LibDatabase.mdf;Integrated Security=True;User Instance=True";
string user = "select CurrentID from CurrentUser";
SqlCommand cmd1 = new SqlCommand(user, con);
con.Open();
string get = cmd1.ExecuteScalar().ToString();
string query1 = "insert into LoanTable(StudId,ISBN,onBorrow) values ("
+ "'" + get + "'" + "," + "'" + tLoanBox.Text + "'" + ","
+ "'" + "1" + "'" + ")";
string numQuery = "select numOfCopies from Items where ISBN='" + tLoanBox.Text + "'";
SqlCommand cmdnumQuery = new SqlCommand(numQuery, con);
SqlCommand cmd2 = new SqlCommand(query1, con);
int result;
int num=Convert.ToInt32(cmdnumQuery.ExecuteScalar());
result = cmd2.ExecuteNonQuery();
if (num > 0)
{
if (result > 0)
Response.Redirect("LoanSuccesfull.aspx");
}
else
notAvailable.Visible = true;
con.Close();
}
}
这是贷款按钮的代码：
protected void bLoanButton_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection();
con.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=D:\\Users\\SUUSER\\Documents\\Visual Studio 2010\\Projects\\Library\\LibWebSite\\App_Data\\LibDatabase.mdf;Integrated Security=True;User Instance=True";
string user = "select CurrentID from CurrentUser";
SqlCommand cmd1 = new SqlCommand(user, con);
con.Open();
string get = cmd1.ExecuteScalar().ToString();
string query1 = "insert into LoanTable(StudId,ISBN,onBorrow) values ("
+ "'" + get + "'" + "," + "'" + tLoanBox.Text + "'" + ","
+ "'" + "1" + "'" + ")";
SqlCommand cmd2 = new SqlCommand(query1, con);
int result;
result = cmd2.ExecuteNonQuery();
if (result > 0)
{
loanSuccesful.Visible = true;
Response.Redirect("LoanSuccesfull.aspx");
}
con.Close();
}
我很感激任何帮助。谢谢