In this article I will explain with an example, how to set ListBox selected value from SQL Server database in ASP.Net using C# and VB.Net.
 
 

Database

I have made use of the following table Hobbies with the schema as follow.
Set ListBox selected value from Database in ASP.Net
 
I have already inserted few records in the table.
Set ListBox selected value from Database in ASP.Net
 
Note: You can download the database table SQL by clicking the download link below.
          Download SQL file
 
 

HTML Markup

The HTML Markup consists of following controls:
ListBox – For displaying selected and unselected item from database.
The ListBox has been assigned with the SelectionMode property set to Multiple.
Hobbies:<br/>
<asp:ListBox ID="lstHobbies" runat="server" SelectionMode="Multiple"></asp:ListBox>
 
 

Namespaces

You will need to import the following namespaces.
C#
using System.Data.SqlClient;
using System.Configuration;
 
VB.Net
Imports System.Data.SqlClient
Imports System.Configuration
 
 

Setting the ListBox selected value from SQL Server database using C# and VB.Net

Inside the Page_Load event handler, first the connection is read from Web.Config file.
Note: For more details on how to read connection string from Web.Config file, please refer my article Read or Write Connection Strings in Web.Config file using ASP.Net using C# and VB.Net.
 
Then, a connection to the database is established using the SqlConnection class.
Then, using ExecuteReader method, the records are fetched from the Hobbies Table and set to the respective properties of ListItem class object.
Note: For more details on how to use ExecuteReader, please refer my article Using SqlCommand ExecuteReader Example in ASP.Net with C# and VB.Net.
 
Finally, the ListItem class object is added to the ListBox and the ListBox with selected value is populated.
C#
protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        string sql = "SELECT HobbyId, Hobby, IsSelected FROM Hobbies";
        string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                con.Open();
                using (SqlDataReader sdr = cmd.ExecuteReader())
                {
                    while (sdr.Read())
                    {
                        ListItem item = new ListItem();
                        // Set the Text.
                        item.Text = sdr["Hobby"].ToString();
                        // Set the Value.
                        item.Value = sdr["HobbyId"].ToString();
                        // Set the Selected value.
                        item.Selected = Convert.ToBoolean(sdr["IsSelected"]);
                        lstHobbies.Items.Add(item);
                    }
                }
                con.Close();
            }
        }
    }
}
 
VB.Net
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim sql As String = "SELECT HobbyId, Hobby, IsSelected FROM Hobbies"
        Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
        Using con As SqlConnection = New SqlConnection(constr)
            Using cmd As SqlCommand = New SqlCommand(sql, con)
                con.Open()
                Using sdr As SqlDataReader = cmd.ExecuteReader()
                    While sdr.Read()
                        Dim item As ListItem = New ListItem()
                        ' Set the Text.
                        item.Text = sdr("Hobby").ToString()
                        ' Set the Value.
                        item.Value = sdr("HobbyId").ToString()
                        ' Set the Selected value.
                        item.Selected = Convert.ToBoolean(sdr("IsSelected"))
                        lstHobbies.Items.Add(item)
                    End While
                End Using
                con.Close()
            End Using
        End Using
    End If
End Sub
 
 

Screenshot

Set ListBox selected value from Database in ASP.Net
 
 

Demo

View Demo
 
 

Downloads

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