The easiest way is to setup the combo's RowSource property to include not
nly the town name, but also the postcode, and then simply extract the
postcode when the town is selected.
Set the combo's Rowsource to:
SELECT TownName, Postcode
FROM tblPostcodes
ORDER BY TownName
Set the combo's ColumnCount property = 2
Set the combo's ColumnWidths property = "3cm;1cm" 'or as appropriate
Then add the following code:
Private Sub cboTownName_AfterUpdate()
If Not IsNull(me!cboTownName) Then
Me!txtPostcode = Nz(Me!cboTownName.Column(1), 0)
End If
End Sub
By the way, if the postcodes are listed in another database, link the table
in which they're stored.
Regards,
Graham R Seach
Microsoft Access MVP
Sydney, Australia