dim n as Integer
If n= 1 Then
QingDang = "销售清单号"
Dim frm As SaleBill = CType(Application.OpenForms("SaleBill"), SaleBill) '窗体1
ElseIf n= 5 Then
QingDang = "进货清单号"
Dim frm As BuyBill = CType(Application.OpenForms("BuyBill"), BuyBill) '窗体2
End If
frm.ListView1.Items.Clear()
sql = "Select * from 销售单 where " & QingDang & " like '" & frm.销售清单号.Text & "'"
...
frm.型号.Text = "型号1 " 'SaleBill.型号.Text = "型号1 " 或者 BuyBill.型号.Text = "型号1 "
If n = 1 Then
frm.数量.Text ="销售数量 "
frm.价格.Text =" "
frm.金额.Text =" "
elseif n=2 then
frm.数量.Text ="进货数量 "
frm.价格.Text =" "
frm.金额.Text =" "
end if
如何让frm能够引用或者设置SaleBill或者BuyBill的控件值。
------解决思路----------------------
不过楼主，要想问题少，并且自己能解决问题，建议还是找本教材系统学习下。关靠搜索，得来的知识太片断化。缺乏体系，随便出个问题都不知道怎么办，都要再去搜，虽然现在搜索很强大，可是有些技巧性的东西，靠搜索也不是全能解决的。
------解决思路----------------------
system.windows.forms.form里面有个controls的collection，里面放了窗体上所有的控件，
但是，注意这个collection是从System.Windows.Forms.Control继承过来的，所以，如果你窗口上的空间放在panel之类的里面的话，单纯遍历form的controls是没用的，要继续遍历panel的control
------解决思路----------------------
另一种方法是如下所示；
Imports System.Data.Sql
Public Class Form1
Private frm As New Form
Private sql As String
Private QingDang As String
Private n As Integer
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
frm.ListView1.Items.Clear()
frm.型号.Text = "型号1 " 'SaleBill.型号.Text = "型号1 " 或者 BuyBill.型号.Text = "型号1 "
If n = 1 Then
QingDang = "销售清单号"
Dim frm As SaleBill = CType(Application.OpenForms("SaleBill"), SaleBill) '窗体1
Sql = "Select * from 销售单 where " & QingDang & " like '" & frm.销售清单号.Text & "'"
frm.数量.Text = "销售数量 "
frm.价格.Text = " "
frm.金额.Text = " "
ElseIf n = 2 Then
QingDang = "进货清单号"
Dim frm As BuyBill = CType(Application.OpenForms("BuyBill"), BuyBill) '窗体2