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Re: Can we solve this -- NFNF and non-1NF at Loggerheads

From: <lauri.pietarinen_at_atbusiness.com>
Date: 6 Feb 2005 13:07:26 -0800
Message-ID: <1107724046.897720.107260_at_l41g2000cwc.googlegroups.com> 






Tom Ivar Helbekkmo wrote:


>

> However, the fact that individual values can be anything means that


it


> is possible to nest relations, and (carefully) add operators to SQL


> that can span the levels, _without breaking the underlying theory_.

>




Well said.  My suspicion is that there is little to gain in
actually storing relations with nested relations, i.e. designing
your database with nested tables.



One possible use for nested tables/relations could be in providing a
richer interface towards application programs and report generators.



I am pasting an example here from a previous thread:



Select FirstName,

       (select company,
               email
           from email_table
           where em_PersonID = PersonID) as Contact


  from Person



With a result like



 FName    Contact

+------------------------+
!Tom  ! +--------------+ !
!     ! !comp1 !a_at_b    ! !
!     ! +------+-------+ !
!     ! !comp2 +c_at_d    ! !
!     ! +--------------+ !
!------------------------!
!Dick ! +--------------+ !
!     ! !comp1 !e_at_f    ! !
!     ! +------+-------+ !
!     ! !comp3 +g_at_h    ! !
!     ! +--------------+ !
!------------------------!
!Harry! +--------------+ !
!     ! +--------------+ !
+------------------------+ 





regards,


Lauri Pietarinen
Received on Sun Feb 06 2005 - 22:07:26 CET












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