How to populate combobox based on another combobox selection item in vb.net With Source Code

Imports System.Data.SqlClient

Public Class Form2

    Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim constr1 As String = "data source=.; initial catalog=names;integrated security=true"

        Using con1 As SqlConnection = New SqlConnection(constr1)

            Using sda1 As SqlDataAdapter = New SqlDataAdapter(" Select id,name from table1", con1)

                Dim dt As DataTable = New DataTable

                sda1.Fill(dt)

                Dim row As DataRow = dt.NewRow()

                row(0) = 0

                row(1) = "Select"

                dt.Rows.InsertAt(row, 0)

                ComboBox1.DataSource = dt

                ComboBox1.DisplayMember = "name"

                ComboBox1.ValueMember = "id"

            End Using

        End Using

    End Sub

    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged

        Dim con1 As SqlConnection = New SqlConnection("Data source=.\;initial catalog=names;integrated security=true")

        con1.Open()

        Dim strsql As String

        strsql = "Select tel from table1 where name='" + ComboBox1.Text + "'"

        Dim cmd As New SqlCommand(strsql, con1)

        Dim myreader As SqlClient.SqlDataReader

        myreader = cmd.ExecuteReader

        ComboBox2.Items.Clear()

        While myreader.Read

            ComboBox2.Items.Add(myreader("tel"))

        End While

        con1.Close()

    End Sub

End Class