录入保存问题

Private Sub 保存1_Click()

Dim DB As DAO.Database
Dim rst As DAO.Recordset
Set DB = CurrentDb()
Set rst = DB.OpenRecordset("录入", dbOpenDynaset)
rst.AddNew
    rst![零件号] = Me!零件号
    rst![数量] = Me!数量
    rst![日期] = Me!日期
If IsNull([零件号]) Then
    MsgBox "没有输入主键"
Else
'更新记录，并弹出提示
    rst.Update
    MsgBox "已经更新！"
End If

rst.Close
Set rst = Nothing

Me.录入子窗体.Requery

Me.零件号 = Null
Me.数量 = Null
Me.日期 = Null
End Sub