Hierarchical XML
XML that comes from a database, whether
generated directly from a DataSet
or through an
XmlDataDocument
, is inherently
relational. That is, each table is represented
by a single element, and its columns are represented by elements
within it. Relations between tables are indicated by foreign key
constraints and row identifiers. This makes perfect sense for
relational data, but sometimes you might want to use a more
hierarchical format.
XML is ideal for representing hierarchical data, because it is itself a tree-oriented format. The data from the coupon database could easily be represented in a combination of relational hierarchical XML structures, as shown in Example 11-12.
<AngusHardware> <customers> <customer_id>1</customer_id> <name>Mark's Roofing</name> <address1>99 Beltline Pkwy</address1> <address2>Suite 100</address2> <city>Wannaque</city> <state>NH</state> <zip>05461 </zip> </customers> <coupons> <coupon_code>077GH </coupon_code> <discount_amount>15</discount_amount> <discount_type>0</discount_type> <expiration_date>2002-11-09T14:17:41.6370000-05:00</expiration_date> </coupons> <coupons> <coupon_code>665RQ </coupon_code> <discount_amount>15</discount_amount> <discount_type>0</discount_type> <expiration_date>2002-11-30T00:00:00.0000000-05:00</expiration_date> <coupon_redemptions> <coupon_code>665RQ </coupon_code> <total_discount>21.5</total_discount> <redemption_date>2002-11-10T00:00:00.0000000-05:00</redemption_date> ...
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