Element type ruler has no subelements. We assume that ruler and country have one
attribute each (name), and ruler nodes are ordered chronologically, that is, in the order
of succession. A document could look like the tree in Figure 1.
Now suppose that data stored according to D1 needs to be restructured according to
the DTD D2 that stores successions that took place in various countries.
europe → succession∗
succession → country ruler successor.
Here we assume that country, ruler, and successor have no subelements but they
have one attribute (name).
Simple attribute-to-attributemappings can establish correspondence between rulers
in D1 and in D2, for example. But for more complex relationships (e.g., if a D1-
document says that country x was ruled by y, then a D2-document should contain
a node succession with country x and ruler y), we need to define structural correspondences
between schemas that simple mappings between attributes (or even paths, as
in Fan and Bohannon [2008]) cannot express.
Standard source-to-target dependencies in relational databases specify how source
patterns are translated into target patterns. It is thus natural to extend this idea to
XML, as indeed was done even for limited mappings we mentioned earlier. Specifically,
we shall use tree patterns that collect attribute values. For example, we can specify the
following mapping between D1 and D2.
Element type ruler has no subelements. We assume that ruler and country have one
attribute each (name), and ruler nodes are ordered chronologically, that is, in the order
of succession. A document could look like the tree in Figure 1.
Now suppose that data stored according to D1 needs to be restructured according to
the DTD D2 that stores successions that took place in various countries.
europe → succession∗
succession → country ruler successor.
Here we assume that country, ruler, and successor have no subelements but they
have one attribute (name).
Simple attribute-to-attributemappings can establish correspondence between rulers
in D1 and in D2, for example. But for more complex relationships (e.g., if a D1-
document says that country x was ruled by y, then a D2-document should contain
a node succession with country x and ruler y), we need to define structural correspondences
between schemas that simple mappings between attributes (or even paths, as
in Fan and Bohannon [2008]) cannot express.
Standard source-to-target dependencies in relational databases specify how source
patterns are translated into target patterns. It is thus natural to extend this idea to
XML, as indeed was done even for limited mappings we mentioned earlier. Specifically,
we shall use tree patterns that collect attribute values. For example, we can specify the
following mapping between D1 and D2.
การแปล กรุณารอสักครู่..

Element type ruler has no subelements. We assume that ruler and country have one
attribute each (name), and ruler nodes are ordered chronologically, that is, in the order
of succession. A document could look like the tree in Figure 1.
Now suppose that data stored according to D1 needs to be restructured according to
the DTD D2 that stores successions that took place in various countries.
europe → succession∗
succession → country ruler successor.
Here we assume that country, ruler, and successor have no subelements but they
have one attribute (name).
Simple attribute-to-attributemappings can establish correspondence between rulers
in D1 and in D2, for example. But for more complex relationships (e.g., if a D1-
document says that country x was ruled by y, then a D2-document should contain
a node succession with country x and ruler y), we need to define structural correspondences
between schemas that simple mappings between attributes (or even paths, as
in Fan and Bohannon [2008]) cannot express.
Standard source-to-target dependencies in relational databases specify how source
patterns are translated into target patterns.ดังนั้นจึงเป็นเรื่องธรรมชาติที่จะขยายแนวคิดนี้
XML เป็นจริงได้แม้แต่ชีวิต เรากล่าวถึงก่อนหน้านี้ โดย
เราจะใช้ต้นไม้รูปแบบที่เก็บค่าแอตทริบิวต์ . ตัวอย่างเช่น เราสามารถระบุ
ต่อไปนี้การทำแผนที่ระหว่าง D1 และ D2 .
การแปล กรุณารอสักครู่..
