David Data (9/28/2010)
OTOH I designed our ETL system with [Postcode] [nvarchar](10) and then had to change it when I found records with postcodes like 'If out please leave by back door or with neighbour at No. 127' 🙁
I really hope your design change was to add a column for "delivery comments", not to increase the maximum length for the postcode. (Unless your business operates in a country where 'If out please leave by back door or with neighbour at No. 127' is a valid postcode).
But I do hope you changed the postcode to varchar(10). As far as I know, all countries in the world that use postal codes limit them to numbers and the letters A-Z.