อยากให้โค้ดเงือนไข Combobox 2 อันดึงจากฐานข้อมูล MS Access

 Private Sub Showcombotypedurg()
        Connectiondata()
        sb = New StringBuilder
        sb.Append("SELECT id_typedrug,n_typedrug FROM typedrug")
        sb.Append("SELECT id_drug,n_drug FROM inventory")
        Dim sqlIni As String = sb.ToString()

        com = New OleDbCommand()
        With com
            .CommandText = sqlIni
            .CommandType = CommandType.Text
            .Connection = Conn
            dr = .ExecuteReader()
        End With

        If dr.HasRows Then
            Dim dtCategories As DataTable
            dtCategories = New DataTable()
            dtCategories.Load(dr)

            With chbntypedrug
                .BeginUpdate()
                .DisplayMember = "n_typedrug"
                .ValueMember = "id_typedrug"
                .DataSource = dtCategories
                .EndUpdate()
            End With

            Dim dtShippers As DataTable
            dtShippers = New DataTable()
            dtShippers.Load(dr)

            With chbndrug
                .BeginUpdate()
                .DisplayMember = "n_drug"
                .ValueMember = "id_drug"
                .DataSource = dtShippers
                .EndUpdate()
            End With
        End If
        dr.Close()

Public Class Form3
    Dim cnn As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\PostCode.mdb;Persist Security Info=True;Jet OLEDB:Database Password=4410210091"
    Private Sub Form3_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        
        ComboBox1.DataSource = GetTableOLEDB("SELECT * FROM Sett_Post_Province", cnn)
        ComboBox2.DataSource = GetTableOLEDB("SELECT * FROM Sett_Post_PostCode", cnn)
    End Sub
    Private Function GetTableOLEDB(SQL As String, strConn As String) As Data.DataTable
        Dim conn As New Data.OleDb.OleDbConnection(strConn)
        Dim ds As New System.Data.DataSet()
        conn.Open()
        Dim strQuery As String = SQL
        Dim adapter As New Data.OleDb.OleDbDataAdapter(strQuery, conn)
        adapter.Fill(ds)
        Return ds.Tables(0)
    End Function

    Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
        ComboBox2.DataSource = GetTableOLEDB("SELECT * FROM Sett_Post_PostCode where Pnv = " & ComboBox1.SelectedValue, cnn)
    End Sub
End Class

 Private Sub CheckAnimal_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        chbntypedrug.DataSource = GetTableOLEDB("SELECT * FROM typedrug", cnn)
        chbndrug.DataSource = GetTableOLEDB("SELECT * FROM inventory", cnn)
end sub
Private Function GetTableOLEDB(SQL As String, strConn As String) As Data.DataTable

        Dim conn As New Data.OleDb.OleDbConnection(strConn)

        Dim ds As New System.Data.DataSet()

        conn.Open()

        Dim strQuery As String = SQL
        Dim adapter As New Data.OleDb.OleDbDataAdapter(strQuery, conn)

        adapter.Fill(ds)

        Return ds.Tables(0)

    End Function
 Private Sub chbntypedrug_SelectedIndexChanged(sender As Object, e As EventArgs) Handles chbntypedrug.SelectedIndexChanged
        chbndrug.DataSource = GetTableOLEDB("SELECT * FROM inventory where n_drug= " & chbndrug.SelectedValue, cnn)
    End Sub

Private Sub showcbdrug()
        da = New OleDbDataAdapter("SELECT DISTINCT n_typedrug From inventory Order By n_typedrug", Conn)
        da.Fill(ds)
        Conn.Close()

        chbntypedrug.DataSource = ds.Tables(0)
        chbntypedrug.DisplayMember = "n_typedrug"
        chbntypedrug.ValueMember = "n_typedrug"
        chbntypedrug.SelectedIndex = -1
    End Sub
    Private Sub chbntypedrug_SelectedIndexChanged(sender As Object, e As EventArgs) Handles chbntypedrug.SelectedIndexChanged
        If chbntypedrug.SelectedIndex > -1 Then
            da = New OleDbDataAdapter("SELECT DISTINCT n_drug From inventory WHERE n_typedrug='" + chbntypedrug.SelectedValue.ToString() + "'", Conn)
            da.Fill(ds)
            Conn.Close()
            chbndrug.DataSource = ds.Tables(0)
            chbndrug.DisplayMember = "n_drug"
            chbndrug.ValueMember = "n_drug"
        End If
    End Sub

Private Sub showcbdrug()
        da = New OleDbDataAdapter("SELECT DISTINCT n_typedrug From inventory Order By n_typedrug", Conn)
        da.Fill(ds)
        Conn.Close()

        chbntypedrug.DataSource = ds.Tables(0)
        chbntypedrug.DisplayMember = "n_typedrug"
        chbntypedrug.ValueMember = "n_typedrug"
        chbntypedrug.SelectedIndex = -1
    End Sub
    Private Sub chbntypedrug_SelectedIndexChanged(sender As Object, e As EventArgs) Handles chbntypedrug.SelectedIndexChanged
        If chbntypedrug.SelectedIndex > -1 Then
            da = New OleDbDataAdapter("SELECT DISTINCT n_drug From inventory WHERE n_typedrug='" + chbntypedrug.SelectedValue.ToString() + "'", Conn)
            da.Fill(ds)
            Conn.Close()
            chbndrug.DataSource = ds.Tables(0)
            chbndrug.DisplayMember = "n_drug"
            chbndrug.ValueMember = "n_drug"
        End If
    End Sub

Private Sub CheckAnimal_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        chbntypedrug.DataSource = GetTableOLEDB("SELECT * FROM typedrug", cnn)
        chbndrug.DataSource = GetTableOLEDB("SELECT * FROM inventory", cnn)
end sub
Private Function GetTableOLEDB(SQL As String, strConn As String) As Data.DataTable

        Dim conn As New Data.OleDb.OleDbConnection(strConn)

        Dim ds As New System.Data.DataSet()

        conn.Open()

        Dim strQuery As String = SQL
        Dim adapter As New Data.OleDb.OleDbDataAdapter(strQuery, conn)

        adapter.Fill(ds)

        Return ds.Tables(0)

    End Function
 Private Sub chbntypedrug_SelectedIndexChanged(sender As Object, e As EventArgs) Handles chbntypedrug.SelectedIndexChanged
        chbndrug.DataSource = GetTableOLEDB("SELECT * FROM inventory where n_typedrug= " & chbndrug.SelectedValue, cnn)
    End Sub

Private Sub chbntypedrug_SelectedIndexChanged(sender As Object, e As EventArgs) Handles chbntypedrug.SelectedIndexChanged
        chbndrug.DataSource = GetTableOLEDB("SELECT * FROM inventory where n_typedrug='" & CStr(chbndrug.SelectedValue) & ")'", cnn)
    End Sub

 Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
        Dim i As Integer
        Dim sqlSale As String = ""
        Dim comTmp As OleDbCommand = New OleDbCommand
        'Dim drTmp As OleDbDataReader
        Dim comsale As OleDbCommand = New OleDbCommand
        For i = 0 To ListView1.Items.Count - 1
            da = New OleDbDataAdapter("INSERT INTO drug(id_order,n_emp,id_drug,n_drug,price_drug,num_drug) VALUES ('" & txtidorder.Text & "'," & chbnemp.Text & "," & CStr(ListView1.Items(i).SubItems(0).Text) & "," & CStr(ListView1.Items(i).SubItems(1).Text) & "," & CInt(ListView1.Items(i).SubItems(3).Text) & "," & CInt(ListView1.Items(i).SubItems(2).Text) & ")", Conn)
            Dim tmpqtybook As Integer
            Dim codedrug As String
            codedrug = ListView1.Items(i).SubItems(0).Text
            sqlSale = "SELECT id_drug,qty FROM inventory Where id_drug ='" & codedrug & "'"
            da = New OleDbDataAdapter(sqlSale, Conn)
            da.Fill(ds, "Pay")
            tmpqtybook = CInt(ds.Tables("Pay").Rows(0).Item("qty"))
            ds.Tables("Pay").Clear()
            sqlSale = "UPDATE inventory"
            sqlSale &= " Set qty = " & tmpqtybook - CInt(ListView1.Items(i).SubItems(2).Text)
            sqlSale &= " where id_drug = '" & codedrug & "'"
            With comsale
                .CommandText = sqlSale
                .ExecuteNonQuery()
            End With
        Next
        MessageBox.Show("บันทึกการส่งจ่ายเรียบร้อยแล้ว", "การสั่งจ่ายเวชภัณฑ์และวัสดุ", MessageBoxButtons.OK, MessageBoxIcon.Information)
    End Sub