ต้องการให้ ข้อมูลใน ฐานข้อมูลไปโชว ใน Combobox ต้องทำไง ครับรบกวนที

Sql = "SELECT * FROM Employee  "
        Dim Cmd As New SqlCommand(Sql, Cls.Con)
        Dim Rs As SqlDataReader = Cmd.ExecuteReader
        If Rs.Read Then
                     combobox1.text=Rs("levell")

              Endif

Imports System.Data.SqlClient
Imports System.Data
Public Class W_Combobox
    Private Function GetASDtbl(ByVal tsql As String) As DataTable 'Function Connect SQL Return DataTable
        GetASDtbl = Nothing
        Dim Con As New SqlConnection
        Dim DTat As SqlDataAdapter
        Dim Dtbl As New DataTable
        Try

            With Con

                If .State = ConnectionState.Open Then .Close()

                .ConnectionString = "server=localhost;uid=sa;pwd=123456;database=7project"

                .Open()

            End With

            DTat = New SqlDataAdapter(tsql, Con)

            DTat.Fill(Dtbl)

            GetASDtbl = Dtbl

        Catch ex As Exception

            MsgBox(ex.Message)

        End Try

    End Function
    Private Function GetAsCombo() As Boolean 'Function Add Combobox
        Dim tsql As String = "SELECT levell FROM Update_sa"
        Dim Dtbl As New DataTable
        Dtbl = GetASDtbl(tsql)
        If ComboBox1.Items.Count > 0 Then
            ComboBox1.Items.Clear()
        End If
        For Each Drow As DataRow In Dtbl.Rows
            ComboBox1.Items.Add(Drow("levell"))
        Next
    End Function

    Private Sub W_Combobox_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 'Form Load

        GetAsCombo()
    End Sub

End Class