Assuming that you're using a form to enter the values and then save them to
the table, you can use the form's BeforeUpdate event to convert a control's
values to uppercase before saving the data to the table.
Private Sub Form_BeforeUpdate(Cancel As Integer)
Me.ControlName.Value = UCase(Me.ControlName.Value)
End Sub
If you have multiple controls that need to have this done, you can add more
code steps using their names.