VB ดึงข้อมูลมาจากฐานข้อมูล แล้วนำมาแสดงใน ComboBox แล้วดึงค่าจากรายการที่เลือก ยังไงคับ

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

        Dim comboBox As comboBox = CType(sender, comboBox)

        Dim selectedEmployee = CType(ComboBox1.SelectedItem, String)

    End Sub 

Imports System.Data.SqlClient
Public Class Form1
    Public data As String = "Data Source=(local);Initial Catalog=test;Persist Security Info=True;User ID=sa;Password=1234"
    Public con As New SqlConnection(Data)
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        If con.State = ConnectionState.Closed Then
            con.Open()
        End If
        Dim sql As String = "SELECT * FROM test_1"
        Dim com As New SqlCommand(sql, con)
        Dim dr As SqlDataReader = com.ExecuteReader
        Dim total As Double
        If dr.HasRows Then
            While dr.Read
                ComboBox1.Items.Add(dr.Item(1))


            End While
            Label1.Text = total
            dr.Close()
        End If
        con.Close()
    End Sub