显示的网格视图数据与从下拉列表中选择的选择不对应 [英] The gridview data displayed is not corresponding to the selection chosen from the dropdownlist
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问题描述
我是C＃的新手。我正在尝试创建一个Web应用程序，允许用户根据他们从下拉列表中选择的主题查看类。我有下拉列表，显示下拉列表中的主题。我所拥有的代码没有向用户显示他们从下拉列表中选择的信息。它显示了相同的gridview数据，无论选择哪个选项。
我尝试过：
这是显示Web应用程序的代码。
I am very new to C#. I am trying to create a web application that will allow users to see classes based on a subject they choose from a drop down list. I have the drop down list displaying subjects from the drop down list. The code that I have isn't showing the user the information they chose from the drop down list. It shows the same gridview data not matter which option is chosen.
What I have tried:
This is the code that will show the web application.
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Summer.aspx.cs" Inherits="Summer" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Summer 2016</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h1>Summer 2016</h1>
<h2>Classes offered</h2>
<h3>Please Choose a Subject</h3>
</div>
<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" DataSourceID="SqlDataSource1" DataTextField="Subjects" DataValueField="Subjects">
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:RegistrationConnectionString %>" SelectCommand="SELECT [Subjects], [Id] FROM [Subjects]">
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="Id" DataSourceID="SqlDataSource2">
<columns>
<asp:BoundField DataField="Id" HeaderText="Id" ReadOnly="True" SortExpression="Id" />
<asp:BoundField DataField="Instrutor" HeaderText="Instrutor" SortExpression="Instrutor" />
<asp:BoundField DataField="CRN" HeaderText="CRN" SortExpression="CRN" />
<asp:BoundField DataField="Credits" HeaderText="Credits" SortExpression="Credits" />
<asp:BoundField DataField="Day" HeaderText="Day" SortExpression="Day" />
<asp:BoundField DataField="Time" HeaderText="Time" SortExpression="Time" />
<asp:BoundField DataField="Title" HeaderText="Title" SortExpression="Title" />
<asp:BoundField DataField="Section" HeaderText="Section" SortExpression="Section" />
<asp:BoundField DataField="Location" HeaderText="Location" SortExpression="Location" />
<asp:BoundField DataField="BeginEnd" HeaderText="BeginEnd" SortExpression="BeginEnd" />
<asp:BoundField DataField="Number" HeaderText="Number" SortExpression="Number" />
<asp:BoundField DataField="SubjectId_Fk" HeaderText="SubjectId_Fk" SortExpression="SubjectId_Fk" />
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:RegistrationConnectionString %>" SelectCommand="SELECT [Id], [Instrutor], [CRN], [Credits], [Day], [Time], [Title], [Section], [Location], [BeginEnd], [Number], [SubjectId_Fk] FROM [Classes]">
<br>
</form>
</body>
</html>
这是应用程序背后的代码。
This is the code behind for the application.
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;
using System.Data;
using System.Configuration;
public partial class Summer : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// DropDownList1.DataSource = GetDataTable();
DropDownList1.DataValueField = "Id";
DropDownList1.DataTextField = "Subjects";
DropDownList1.DataBind();
}
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
using (SqlConnection Cn = new SqlConnection(ConfigurationManager.ConnectionStrings[@"C:\Users\Keith\Documents\Registration.mdf"].ConnectionString))
{
using (SqlCommand Cmd = new SqlCommand("select * from Classes where Id=" + DropDownList1.SelectedValue.ToString(), Cn))
{
Cn.Open();
Cmd.Parameters.AddWithValue("@Id", int.Parse(DropDownList1.SelectedValue));
SqlDataReader Dr = Cmd.ExecuteReader();
if (Dr.HasRows)
{
GridView1.DataSource = Dr;
GridView1.DataBind();
}
Dr.Close();
Cn.Close();
}
}
}
public static DataTable GetDataTable(string sqlCommand)
{
DataTable table = new DataTable();
try
{
using (SqlConnection myConnection = new SqlConnection(ConfigurationManager.ConnectionStrings[@"C:\Users\Keith\Documents\Registration.mdf"].ConnectionString))
{
using (SqlCommand cmd = new SqlCommand(sqlCommand, myConnection))
{
using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))
{
adapter.Fill(table);
}
}
}
}
catch (Exception ex)
{
table = null;
throw ex;
}
return table;
}
}
推荐答案
ConnectionStrings：RegistrationConnectionString ％> SelectCommand = SELECT [Subjects]，[Id] FROM [Subjects] >
< asp：GridView ID = GridView1 runat = 服务器 AutoGenerateColumns = False DataKeyNames = Id DataSourceID = SqlDataSource2 >
< 列 >
< asp：BoundField DataField = Id < span class =code-attribute> HeaderText = Id ReadOnly = 真 SortExpression = Id / >
< asp：BoundField DataField = Instrutor HeaderText = Instrutor < span class =code-attribute> SortExpression = Instrutor / >
< < span class =code-leadattribute> asp：BoundField DataField = CRN HeaderText = CRN SortExpression = CRN < span class =code-attribute> / >
< asp：BoundField DataField =Credits HeaderText = 积分 SortExpression = Credits / >
< asp：BoundField DataField = 日 HeaderText = 日 SortExpression = 日 / >
< asp：BoundField DataField = 时间 HeaderText = 时间 SortExpression = 时间 / >
< asp：BoundField DataField = 标题 HeaderText = 标题 SortExpression = 标题 / >
< asp：BoundField DataField = HeaderText = 秒 SortExpression = 部分 / >
< asp：BoundField < span class =code-attribute> DataField = Location HeaderText = 位置 SortExpression = 位置 / >
< asp：BoundField DataField = BeginEnd HeaderText = BeginEnd SortExpression = BeginEnd / < span class =code-keyword>>
< asp：BoundField DataField = 数字 HeaderText = 编号 SortExpression = 数字 / >
<asp:BoundField< span class=\"code-attribute\"> DataField=\"SubjectId_Fk\" HeaderText= \"SubjectId_Fk\" SortExpression =\"SubjectId_Fk\" />
<asp:SqlDataSource ID=\"SqlDataSource2\" runat=\"server\" ConnectionString=\"<%
ConnectionStrings:RegistrationConnectionString %>" SelectCommand="SELECT [Subjects], [Id] FROM [Subjects]"> <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="Id" DataSourceID="SqlDataSource2"> <columns> <asp:BoundField DataField="Id" HeaderText="Id" ReadOnly="True" SortExpression="Id" /> <asp:BoundField DataField="Instrutor" HeaderText="Instrutor" SortExpression="Instrutor" /> <asp:BoundField DataField="CRN" HeaderText="CRN" SortExpression="CRN" /> <asp:BoundField DataField="Credits" HeaderText="Credits" SortExpression="Credits" /> <asp:BoundField DataField="Day" HeaderText="Day" SortExpression="Day" /> <asp:BoundField DataField="Time" HeaderText="Time" SortExpression="Time" /> <asp:BoundField DataField="Title" HeaderText="Title" SortExpression="Title" /> <asp:BoundField DataField="Section" HeaderText="Section" SortExpression="Section" /> <asp:BoundField DataField="Location" HeaderText="Location" SortExpression="Location" /> <asp:BoundField DataField="BeginEnd" HeaderText="BeginEnd" SortExpression="BeginEnd" /> <asp:BoundField DataField="Number" HeaderText="Number" SortExpression="Number" /> <asp:BoundField DataField="SubjectId_Fk" HeaderText="SubjectId_Fk" SortExpression="SubjectId_Fk" /> <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%
ConnectionStrings:RegistrationConnectionString %>\" Select Command=\"SELECT [Id], [Instrutor], [CRN], [Credits], [Day], [Time], [Title], [Section], [Location], [BeginEnd], [Number], [SubjectId_Fk] FROM [Classes]\">
<br>
</form>
</body>
</html>
ConnectionStrings:RegistrationConnectionString %>" SelectCommand="SELECT [Id], [Instrutor], [CRN], [Credits], [Day], [Time], [Title], [Section], [Location], [BeginEnd], [Number], [SubjectId_Fk] FROM [Classes]"> <br> </form> </body> </html>
This is the code behind for the application.
This is the code behind for the application.
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;
using System.Data;
using System.Configuration;
public partial class Summer : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// DropDownList1.DataSource = GetDataTable();
DropDownList1.DataValueField = "Id";
DropDownList1.DataTextField = "Subjects";
DropDownList1.DataBind();
}
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
using (SqlConnection Cn = new SqlConnection(ConfigurationManager.ConnectionStrings[@"C:\Users\Keith\Documents\Registration.mdf"].ConnectionString))
{
using (SqlCommand Cmd = new SqlCommand("select * from Classes where Id=" + DropDownList1.SelectedValue.ToString(), Cn))
{
Cn.Open();
Cmd.Parameters.AddWithValue("@Id", int.Parse(DropDownList1.SelectedValue));
SqlDataReader Dr = Cmd.ExecuteReader();
if (Dr.HasRows)
{
GridView1.DataSource = Dr;
GridView1.DataBind();
}
Dr.Close();
Cn.Close();
}
}
}
public static DataTable GetDataTable(string sqlCommand)
{
DataTable table = new DataTable();
try
{
using (SqlConnection myConnection = new SqlConnection(ConfigurationManager.ConnectionStrings[@"C:\Users\Keith\Documents\Registration.mdf"].ConnectionString))
{
using (SqlCommand cmd = new SqlCommand(sqlCommand, myConnection))
{
using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))
{
adapter.Fill(table);
}
}
}
}
catch (Exception ex)
{
table = null;
throw ex;
}
return table;
}
}Don’t think you need the Cn.Open() in the GetData function. This works for me:
Don't think you need the Cn.Open() in the GetData function. This works for me:
public static DataTable GetDataTable(string sqlCommand)
{
DataTable table = new DataTable();
try
{
using (SqlConnection myConnection = new SqlConnection(ConfigurationManager.ConnectionStrings[@"C:\Users\Keith\Documents\Registration.mdf"].ConnectionString))
{
using (SqlCommand cmd = new SqlCommand(sqlCommand, myConnection))
{
using (SqlDataAdapter adapter = new SqlDataAdapter(cmd))
{
adapter.Fill(table);
}
}
}
}
catch (Exception ex)
{
table = null;
throw ex;
}
return table;
}
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