Visual Studio 2017, Asp.net, c# DropDownList Control, How to Refresh Text Boxes After a New Value is Selected
Question
How to execute a sql statement and refresh the textboxes after user selects a new value from the drop down list. I have an asp page that allows the user to select another course from the dropdownlist control. After the user changes the selection I want to get the ID of the course and select that record from the database. Then I want to refresh the textboxes that are used to display the course. The page is only used to display the course and generate a unique code to verify attendance.
Visual Studio 2017 Community, Asp.net 4.6, Ado, c#, Microsoft SQL Server 2016
The page is only used to display the course and generate a unique code to verify attendance. I've tried the index change event but I don't need to post data back to the database.
instructorcourse.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="instructorcourse.aspx.cs" Inherits="updatecourses" %>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head3" runat="server">
<title>Update Course</title>
<style type="text/css">
.auto-style1 {
width: 660px;
}
.auto-style2 {
width: 132px;
}
</style>
</head>
<body>
<form id="form3" runat="server">
<h2>
</h2>
<h2>
Attendance On Grounds</h2>
<h2>
Instructor</h2>
<h2>
Next Course</h2>
<table>
<tr>
<td>Record ID</td>
<td class="auto-style2">
<asp:TextBox ID="txtRecordID" runat="server"></asp:TextBox>
</td>
<td class="auto-style1">
<asp:Button ID="btnGetDetails" runat="server" Text="Get RecordID" OnClick="btnGetDetails_Click" Width="131px" />
<-will select next course on form load, by hostid, will go in form load</td>
</tr>
<tr>
<td>
Insctructor ID:</td>
<td class="auto-style2">
<asp:TextBox ID="txtIntructorid" runat="server"></asp:TextBox></td>
<td class="auto-style1">
</td>
</tr>
<tr>
<td>
Instructor Name:</td>
<td class="auto-style2">
<asp:TextBox ID="txtInstructorName" runat="server"></asp:TextBox></td>
<td class="auto-style1">
<asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="SqlDataSourceDropDownList" DataTextField="InstructorName" DataValueField="RecordID">
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSourceDropDownList" runat="server" ConnectionString="<%$ ConnectionStrings:AdoNetCrudWebSite %>" SelectCommand="SELECT DISTINCT [RecordID], [InstructorName] FROM [attendance]"></asp:SqlDataSource>
<-drop down, if change, new name then lookup id, and refill textboxes</td>
</tr>
<tr>
<td>
Course Code:</td>
<td class="auto-style2">
<asp:TextBox ID="txtCourseCode" runat="server"></asp:TextBox></td>
<td class="auto-style1">
</td>
</tr>
<tr>
<td>
Course Title:</td>
<td class="auto-style2">
<asp:TextBox ID="txtCourseTitle" runat="server"></asp:TextBox></td>
<td class="auto-style1">
</td>
</tr>
<tr>
<td>
Attendance Code: </td>
<td class="auto-style2">
<asp:TextBox ID="txtAttendanceCode" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Generate Code" />
</td>
<td class="auto-style1">
</td>
</tr>
</table>
<br />
<asp:Button ID="btnUpdate" runat="server" Text="Update Course" Enabled="false" OnClick="btnUpdate_Click" Visible="False" /><br />
<br />
<asp:Label ID="Label2" runat="server" EnableViewState="False"></asp:Label><br />
<p />
<a href="homepage.aspx">Go Back To Menu</a>
</form>
</body>
</html>
instructorcourse.aspx.cs
using System.Data;
using System.Data.SqlClient;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class updatecourses : System.Web.UI.Page
{
protected void btnGetDetails_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(Database.ConnectionString);
try
{
con.Open();
SqlCommand cmd = new SqlCommand("select * from courses", con);
cmd.Parameters.AddWithValue("@RecordID", txtRecordID.Text);
SqlDataReader dr = cmd.ExecuteReader();
if (dr.Read())
{
// display data in textboxes
txtIntructorid.Text = dr["instructorid"].ToString();
txtInstructorName.Text = dr["InstructorName"].ToString();
txtCourseCode.Text = dr["CourseCode"].ToString();
txtCourseTitle.Text = dr["CourseTitle"].ToString();
txtAttendanceCode.Text = dr["AttendanceCode"].ToString();
btnUpdate.Enabled = true;
}
else
{
//lblMsg.Text = "Sorry! Invalid attendance Id";
btnUpdate.Enabled = false;
}
dr.Close();
}
catch (Exception ex)
{
//lblMsg.Text = "Error --> " + ex.Message;
}
finally
{
con.Close();
}
}
protected void btnUpdate_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(Database.ConnectionString);
try
{
con.Open();
SqlCommand cmd = new SqlCommand("update courses set InstructorID=@InstructorID, InstructorName = @InstructorName, CourseCode = @CourseCode, CourseTitle = @CourseTitle, AttendanceCode = @AttendanceCode where RecordID = @RecordID", con);
//cmd.Parameters.AddWithValue("@CourseID", txtCourseID.Text);
cmd.Parameters.AddWithValue("@InstructorID", txtIntructorid.Text);
cmd.Parameters.AddWithValue("@InstructorName", txtInstructorName.Text);
cmd.Parameters.AddWithValue("@CourseCode", txtCourseCode.Text);
cmd.Parameters.AddWithValue("@CourseTitle", txtCourseTitle.Text);
cmd.Parameters.AddWithValue("@AttendanceCode", txtAttendanceCode.Text);
if (cmd.ExecuteNonQuery() == 1)
{
//lblMsg.Text = "Updated Successfully!";
}
else
{
//lblMsg.Text = "Sorry! Could not update";
}
}
catch (Exception ex)
{
//lblMsg.Text = "Error --> " + ex.Message;
}
finally
{
con.Close();
}
}
protected void Button1_Click(object sender, EventArgs e)
{
}
}
database create script
USE [master]
GO
/****** Object: Database [AdoNetCrudWebSite] Script Date: 1/25/2019 9:49:34 AM ******/
CREATE DATABASE [AdoNetCrudWebSite]
CONTAINMENT = NONE
ON PRIMARY
( NAME = N'AdoNetCrudWebSite', FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER2016\MSSQL\DATA\AdoNetCrudWebSite.mdf' , SIZE = 8192KB , MAXSIZE = UNLIMITED, FILEGROWTH = 65536KB )
LOG ON
( NAME = N'AdoNetCrudWebSite_log', FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER2016\MSSQL\DATA\AdoNetCrudWebSite_log.ldf' , SIZE = 8192KB , MAXSIZE = 2048GB , FILEGROWTH = 65536KB )
GO
ALTER DATABASE [AdoNetCrudWebSite] SET COMPATIBILITY_LEVEL = 130
GO
IF (1 = FULLTEXTSERVICEPROPERTY('IsFullTextInstalled'))
begin
EXEC [AdoNetCrudWebSite].[dbo].[sp_fulltext_database] @action = 'enable'
end
GO
ALTER DATABASE [AdoNetCrudWebSite] SET ANSI_NULL_DEFAULT OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET ANSI_NULLS OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET ANSI_PADDING OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET ANSI_WARNINGS OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET ARITHABORT OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET AUTO_CLOSE OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET AUTO_SHRINK OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET AUTO_UPDATE_STATISTICS ON
GO
ALTER DATABASE [AdoNetCrudWebSite] SET CURSOR_CLOSE_ON_COMMIT OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET CURSOR_DEFAULT GLOBAL
GO
ALTER DATABASE [AdoNetCrudWebSite] SET CONCAT_NULL_YIELDS_NULL OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET NUMERIC_ROUNDABORT OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET QUOTED_IDENTIFIER OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET RECURSIVE_TRIGGERS OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET DISABLE_BROKER
GO
ALTER DATABASE [AdoNetCrudWebSite] SET AUTO_UPDATE_STATISTICS_ASYNC OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET DATE_CORRELATION_OPTIMIZATION OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET TRUSTWORTHY OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET ALLOW_SNAPSHOT_ISOLATION OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET PARAMETERIZATION SIMPLE
GO
ALTER DATABASE [AdoNetCrudWebSite] SET READ_COMMITTED_SNAPSHOT OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET HONOR_BROKER_PRIORITY OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET RECOVERY FULL
GO
ALTER DATABASE [AdoNetCrudWebSite] SET MULTI_USER
GO
ALTER DATABASE [AdoNetCrudWebSite] SET PAGE_VERIFY CHECKSUM
GO
ALTER DATABASE [AdoNetCrudWebSite] SET DB_CHAINING OFF
GO
ALTER DATABASE [AdoNetCrudWebSite] SET FILESTREAM( NON_TRANSACTED_ACCESS = OFF )
GO
ALTER DATABASE [AdoNetCrudWebSite] SET TARGET_RECOVERY_TIME = 60 SECONDS
GO
ALTER DATABASE [AdoNetCrudWebSite] SET DELAYED_DURABILITY = DISABLED
GO
EXEC sys.sp_db_vardecimal_storage_format N'AdoNetCrudWebSite', N'ON'
GO
ALTER DATABASE [AdoNetCrudWebSite] SET QUERY_STORE = OFF
GO
USE [AdoNetCrudWebSite]
GO
ALTER DATABASE SCOPED CONFIGURATION SET MAXDOP = 0;
GO
ALTER DATABASE SCOPED CONFIGURATION FOR SECONDARY SET MAXDOP = PRIMARY;
GO
ALTER DATABASE SCOPED CONFIGURATION SET LEGACY_CARDINALITY_ESTIMATION = OFF;
GO
ALTER DATABASE SCOPED CONFIGURATION FOR SECONDARY SET LEGACY_CARDINALITY_ESTIMATION = PRIMARY;
GO
ALTER DATABASE SCOPED CONFIGURATION SET PARAMETER_SNIFFING = ON;
GO
ALTER DATABASE SCOPED CONFIGURATION FOR SECONDARY SET PARAMETER_SNIFFING = PRIMARY;
GO
ALTER DATABASE SCOPED CONFIGURATION SET QUERY_OPTIMIZER_HOTFIXES = OFF;
GO
ALTER DATABASE SCOPED CONFIGURATION FOR SECONDARY SET QUERY_OPTIMIZER_HOTFIXES = PRIMARY;
GO
USE [AdoNetCrudWebSite]
GO
/****** Object: Table [dbo].[attendance] Script Date: 1/25/2019 9:49:35 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[attendance](
[RecordID] [int] IDENTITY(1,1) NOT NULL,
[InstructorID] [varchar](50) NULL,
[InstructorName] [varchar](200) NULL,
[CourseCode] [varchar](50) NULL,
[CourseTitle] [varchar](50) NULL,
[AttendanceCode] [varchar](50) NULL,
CONSTRAINT [PK_attendance] PRIMARY KEY CLUSTERED
(
[RecordID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
/****** Object: Table [dbo].[courses] Script Date: 1/25/2019 9:49:35 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[courses](
[RecordID] [int] IDENTITY(1,1) NOT NULL,
[InstructorID] [varchar](50) NULL,
[InstructorName] [varchar](200) NULL,
[CourseCode] [varchar](50) NULL,
[CourseTitle] [varchar](50) NULL,
[AttendanceCode] [varchar](50) NULL,
CONSTRAINT [PK_books] PRIMARY KEY CLUSTERED
(
[RecordID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
USE [master]
GO
ALTER DATABASE [AdoNetCrudWebSite] SET READ_WRITE
GO
1 answers
solution1
0 ACCPTED 2019-01-25 19:31:27
I think you are trying to AutoPostBack="true" when you change the Value of DropDownList, for this you can use UpdatePanel and Triggers it OnSelectedIndexChanged event and inside that even you can specify your logic.
<asp:ScriptManager ID="MainScriptManager" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel2" runat="server">
<ContentTemplate>
<asp:DropDownList ID="DropDownList1" AutoPostBack="true" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" DataSourceID="SqlDataSourceDropDownList" DataTextField="InstructorName" DataValueField="RecordID">
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSourceDropDownList" runat="server" ConnectionString="<%$ ConnectionStrings:AdoNetCrudWebSite %>" SelectCommand="SELECT DISTINCT [RecordID], [InstructorName] FROM [attendance]"></asp:SqlDataSource>
<asp:TextBox ID="TextBox1" runat="server">TextBox you want to change</asp:TextBox>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="DropDownList1" EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>
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