Thanks Pat, I have three tables using one to many. I just found i didn't set the "Recordset Type" to "Dynaset (Inconsistent Updates)". It works after changing it to "Dynaset (Inconsistent Updates)" from "Dynaset". Thank you very much.
When I use a "delete" command button to delete a record in form, it works well. But this record is still in my table. How to delete record directly from table? Thanks