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RE: Database schema from standards xsd

From: Michael Kay <mike@saxonica.com>
Date: Thu, 3 Apr 2008 18:48:33 +0800
To: "'Boris Kolpackov'" <boris@codesynthesis.com>
Cc: "'Mansour Al Akeel'" <mansour.alakeel@gmail.com>, <xmlschema-dev@w3.org>
Message-ID: <018001c89578$44c98210$e4f9a8c0@turtle>

> There are ways to specify in XML Schema whether elements 
> should appear in a particular order or not (xs:sequence vs 
> xs:all). What you are probably saying here is that if the 
> schema says that elements can appear in any order, it does 
> not mean that the actual order of elements as they appear in 
> XML documents is insignificant to the application logic.

What I meant was that if you say

<xs:element name="authors">
  <xs:complexType>
    <xs:element name="author" maxOccurs="unbounded"/>
  </xs:complexType>
</xs:element>

then there is no way of knowing whether the order of the authors is
important. Because in the relational model tuples are unordered, significant
order needs to be represented in some other way, for example with integer
sequence numbers - which isn't an ideal representation if the sequence also
needs to be updateable.

Michael Kay
    
Received on Thursday, 3 April 2008 10:49:13 UTC

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