如何将焦点转移到子窗体--变速箱采购订单部分代码

Private Sub saveData()
'新增报销数据子程序
    Dim rst As DAO.Recordset
    '如果保存时，别的操作员新增了此编号，则生成新的编号
    If Acchelp_StrDataIsExist("tblcgdd", "cgddid", Me.cgddid) = True Then
        '生成新的编号
        AutoMxID
    End If
    If IsNull(Me.gysid) Then
        MsgBox "请选择供应商", vbCritical, "提示"
        Me.gysid.SetFocus
        Exit Sub
    End If
   
    If IsNull(Me.lxr1) Then
        MsgBox "请输入联系人", vbCritical, "提示"
        Me.lxr1.SetFocus
        Exit Sub
    End If
       
    If IsNull(Me.dhrq) Then
        MsgBox "请输入订货日期", vbCritical, "提示"
        Me.dhrq.SetFocus
        Exit Sub
    End If
    If IsNull(Me.zzrq) Then
        MsgBox "请输入最早交货日期", vbCritical, "提示"
        Me.zzrq.SetFocus
        Exit Sub
    End If
    If IsNull(Me.zcrq) Then
        MsgBox "请输入最晚交货日期", vbCritical, "提示"
        Me.zcrq.SetFocus
        Exit Sub
    End If
    
     '如何将焦点转移到子窗体，并运行以下两个IF 语句？？？？？？
 
    
     If IsNull(Me.ljid) Then
        MsgBox "请输入零件名称", vbCritical, "提示"
        Me.ljid.SetFocus
        Exit Sub
    End If
   
    If IsNull(Me.sl) Then
        MsgBox "请输入零件数量", vbCritical, "提示"
        Me.sl.SetFocus
        Exit Sub
    End If
   
   
    If MsgBox("您确认要保存吗?", vbOKCancel + vbInformation, "提示") = vbOK Then
        '在保存之前刷新窗体
        Me.Refresh
        '打开tblcgdd表
        Set rst = CurrentDb.OpenRecordset("tblcgdd", dbOpenDynaset)
      
   
        '新增一行数据
        rst.AddNew
        rst("cgddid") = Me.cgddid
        rst("gysid") = Me.gysid
        rst("lxr1") = Me.lxr1
        rst("cgddrq") = Me.dhrq
        rst("zzrq") = Me.zzrq
        rst("zcrq") = Me.zcrq
        '操作员,czyid的字段大小务必为6，请检查
        rst("czyid") = Forms!usysfrmLogin!txtUserName
        rst.Update
        rst.Close
        Set rst = Nothing
       
       
      
         If Me.fxsblj = -1 Then
             '将tblXsddsblj_temp表中的数据追加到tblXsddsblj表中
            DoCmd.SetWarnings False
            DoCmd.RunSQL "INSERT INTO tblcgmx SELECT tblcgmx_temp.* FROM tblcgmx_temp;"
         End If
        '刷新数据,通过重新加载子窗体实现
        If IsLoaded("usysfrmMain") Then
            DoCmd.Echo False
            Forms!usysfrmMain!frmChild.SourceObject = "frmcgdd_child"
            DoCmd.Echo True
        End If
        MsgBox "保存成功!", vbInformation, "提示"
        '清空，以便录入新记录
        Me.gysid = Null
        Me.lxr1 = Null
        Me.dhrq = Date
        Me.zzrq = Date + 10
        Me.zcrq = Date + 25
        '让khid获得焦点，不然如果焦点停留在frmChild上，会出错
        Me.gysid.SetFocus
        '生成新的编号
        AutoMxID
        If Me.fxsblj = -1 Then
           '清空三包零件临时表 tblXsddsblj_temp
            DoCmd.SetWarnings False
            DoCmd.RunSQL "DELETE tblcgmx_temp.* FROM tblcgmx_temp;"
        End If
        Me.fxsblj = 0
        '子窗体不可新增数据
        Me.frmChild.Form.AllowAdditions = False
       
        Me.gysid.SetFocus
    End If
    End Sub