Check If Their Is A New Entry

Hi..

I have a form with a subform where the user has to enter some data in them. when the user moves to the subform the data in the form automatically get saved in the table(you all know that i suppose).
In the form i have a back button where the user is able to go back to the main form.the code of the button is:


If MsgBox("Do you want to save before exit?", vbYesNo, "Save") = vbYes Then
DoCmd.RunCommand acCmdSave
MsgBox ("Data has been saved.")
DoCmd.Close
DoCmd.OpenForm "Main"
Else
DoCmd.RunCommand acCmdDeleteRecord
DoCmd.Close
DoCmd.OpenForm "Main"
End If
Else
DoCmd.Close
DoCmd.OpenForm "Main"
End If


my problem is when the user hasn't entered any data and wants to return i would get an error (because i'm trying to delete a record which doesn't exist
) how can i check if a record has been eneterd.
if new entry then
deleterecord,close,open mainform
else
close,open main form
endif

thankxx in advance..
hope my grammer is correct