SQL & PL/SQL

select zipcode from zipcode_hr where REGEXP_LIKE(zipcode, '([[:digit:]]{5})(-[[:digit:]]{4})?$')

I am trying to find out the US zip code format from the regular expression above is the query ...

US Zip code format : either 5 digit number or 5 digitnumber - 4 digit number ( EX: 12345 or 12345-6789 )

above expression is giving results like this ( 12345-6789 ) and with five digit number too. and the problem is with five digit numbers results contains some 6 digit and 7 digit numbers.

Can any one provide help on this.

Ref Link : http://www.oracle.com/technology/oramag/webcolumns/2003/techarticles/rischert_regexp_pt1.html

And if possible can any one give the Reg Ex for Canada Zip code.

Thanks in Advance.
Santhosh