Save multiple selected items of ASP.Net ListBox using C# and VB.Net

Hi sanjayjp13,

Check this example. Now please take its reference and correct your code.

Database

For this example I have used of Northwind database that you can download using the link given below.

Download Northwind Database

HTML

<asp:ListBox ID="lbCountries" runat="server" Width="200px" SelectionMode="Multiple">
</asp:ListBox>
<br />
<asp:Button Text="Get Selected Item" runat="server" OnClick="GetSelectedItem" />

Namespaces

C#

using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Text;

VB.Net

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.Text

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        PopulateCountries();
    }
}

private void PopulateCountries()
{
    using (SqlConnection conn = new SqlConnection())
    {
        conn.ConnectionString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = "SELECT TOP 10 CustomerID,Country FROM Customers";
            cmd.Connection = conn;
            conn.Open();
            DataTable dt = new DataTable();
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                da.Fill(dt);
                lbCountries.DataSource = dt;
                lbCountries.DataTextField = "Country";
                lbCountries.DataValueField = "CustomerID";
                lbCountries.DataBind();
            }
            conn.Close();
        }
    }
}

protected void GetSelectedItem(object sender, EventArgs e)
{
    StringBuilder sb = new StringBuilder();
    foreach (ListItem item in lbCountries.Items)
    {
        if (item.Selected)
        {
            sb.Append(item.Text + ",");
        }
    }
    Response.Write(sb.ToString().Remove(sb.ToString().Length - 1));
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        PopulateCountries()
    End If
End Sub

Private Sub PopulateCountries()
    Using conn As SqlConnection = New SqlConnection()
        conn.ConnectionString = ConfigurationManager.ConnectionStrings("constr").ConnectionString
        Using cmd As SqlCommand = New SqlCommand()
            cmd.CommandText = "SELECT TOP 10 CustomerID,Country FROM Customers"
            cmd.Connection = conn
            conn.Open()
            Dim dt As DataTable = New DataTable()
            Using da As SqlDataAdapter = New SqlDataAdapter(cmd)
                da.Fill(dt)
                lbCountries.DataSource = dt
                lbCountries.DataTextField = "Country"
                lbCountries.DataValueField = "CustomerID"
                lbCountries.DataBind()
            End Using
            conn.Close()
        End Using
    End Using
End Sub

Protected Sub GetSelectedItem(ByVal sender As Object, ByVal e As EventArgs)
    Dim sb As StringBuilder = New StringBuilder()
    For Each item As ListItem In lbCountries.Items
        If item.Selected Then
            sb.Append(item.Text & ",")
        End If
    Next
    Response.Write(sb.ToString().Remove(sb.ToString().Length - 1))
End Sub

Screenshot