Re: relational and hierarchical database
Date: 27 Nov 2001 10:24:40 -0800
Message-ID: <661b2f41.0111271024.69258c14_at_posting.google.com>
barthelmes_s_at_ibb.de (S. Barthelmes) wrote in message news:<f8ddfc25.0111270104.2b1b2a60_at_posting.google.com>...
> Can anyone please explan me the main differences between a relational
> and a hierarchical database?
>
> Thanks, S.
The simplest difference between a hierarchical and relational can be stated as follows:
Hierarchical database model:
It is based on hierarchy. Hierarchy is based on Parent-Child
Relationship.
Parent-Child Relationship Type is basically 1:N relationship. The
schema for a hierarchy has a single root. To represent M:N
relationship in a hierarchical structure, we must allow duplication of
child record instances.
Relational Database model:
A relational database is a collection of time-varying, normalized relations of assorted degrees.
A relational database consists of a collection of tables. All data values are atomic. No repeating groups are allowed. A relational database is a pointerless database, User does not see or is made aware of pointers.
Hope this helps.
Prashanth. Received on Tue Nov 27 2001 - 19:24:40 CET