free barcode addin for excel 2007 Storage of XML Data in Software

Create USS Code 128 in Software Storage of XML Data

106 Storage of XML Data
Printing Code 128 Code Set C In None
Using Barcode drawer for Software Control to generate, create Code 128C image in Software applications.
Read Code 128 Code Set C In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
Many applications require storage of XML data One way to store XML data is to convert it to relational representation, and store it in a relational database There are several alternatives for storing XML data, brie y outlined here
Code 128 Code Set A Drawer In Visual C#
Using Barcode drawer for VS .NET Control to generate, create Code-128 image in Visual Studio .NET applications.
Drawing Code 128C In .NET
Using Barcode drawer for ASP.NET Control to generate, create ANSI/AIM Code 128 image in ASP.NET applications.
1061 Relational Databases
Generate Code 128 Code Set A In .NET
Using Barcode creator for .NET Control to generate, create Code 128C image in .NET applications.
Paint Code 128 Code Set C In VB.NET
Using Barcode drawer for .NET framework Control to generate, create USS Code 128 image in .NET applications.
Since relational databases are widely used in existing applications, there is a great bene t to be had in storing XML data in relational databases, so that the data can be accessed from existing applications
Painting Bar Code In None
Using Barcode creation for Software Control to generate, create bar code image in Software applications.
Universal Product Code Version A Generator In None
Using Barcode printer for Software Control to generate, create GS1 - 12 image in Software applications.
Silberschatz Korth Sudarshan: Database System Concepts, Fourth Edition
EAN / UCC - 13 Generation In None
Using Barcode drawer for Software Control to generate, create GS1 128 image in Software applications.
UPC - 13 Generator In None
Using Barcode printer for Software Control to generate, create GS1 - 13 image in Software applications.
III Object Based Databases and XML
Drawing Barcode In None
Using Barcode printer for Software Control to generate, create bar code image in Software applications.
Drawing ECC200 In None
Using Barcode generation for Software Control to generate, create Data Matrix ECC200 image in Software applications.
10 XML
Identcode Drawer In None
Using Barcode creator for Software Control to generate, create Identcode image in Software applications.
Making Data Matrix In None
Using Barcode generation for Online Control to generate, create Data Matrix ECC200 image in Online applications.
The McGraw Hill Companies, 2001
Make Code 3/9 In Java
Using Barcode printer for Eclipse BIRT Control to generate, create USS Code 39 image in BIRT applications.
Code 128 Code Set A Recognizer In C#
Using Barcode decoder for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications.
10
Decode ANSI/AIM Code 128 In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
Print Code-128 In Objective-C
Using Barcode creator for iPad Control to generate, create USS Code 128 image in iPad applications.
Converting XML data to relational form is usually straightforward if the data were generated from a relational schema in the rst place, and XML was used merely as a data exchange format for relational data However, there are many applications where the XML data is not generated from a relational schema, and translating the data to relational form for storage may not be straightforward In particular, nested elements and elements that recur (corresponding to set valued attributes) complicate storage of XML data in relational format Several alternative approaches are available: Store as string A simple way to store XML data in a relational database is to store each child element of the top-level element as a string in a separate tuple in the database For instance, the XML data in Figure 101 could be stored as a set of tuples in a relation elements(data), with the attribute data of each tuple storing one XML element (account, customer, or depositor) in string form While the above representation is easy to use, the database system does not know the schema of the stored elements As a result, it is not possible to query the data directly In fact, it is not even possible to implement simple selections such as nding all account elements, or nding the account element with account number A-401, without scanning all tuples of the relation and examining the contents of the string stored in the tuple A partial solution to this problem is to store different types of elements in different relations, and also store the values of some critical elements as attributes of the relation to enable indexing For instance, in our example, the relations would be account-elements, customer-elements, and depositor-elements, each with an attribute data Each relation may have extra attributes to store the values of some subelements, such as account-number or customer-name Thus, a query that requires account elements with a speci ed account number can be answered ef ciently with this representation Such an approach depends on type information about XML data, such as the DTD of the data Some database systems, such as Oracle 9, support function indices, which can help avoid replication of attributes between the XML string and relation attributes Unlike normal indices, which are on attribute values, function indices can be built on the result of applying user-de ned functions on tuples For instance, a function index can be built on a user-de ned function that returns the value of the account-number subelement of the XML string in a tuple The index can then be used in the same way as an index on a account-number attribute The above approaches have the drawback that a large part of the XML information is stored within strings It is possible to store all the information in relations in one of several ways which we examine next Tree representation Arbitrary XML data can be modeled as a tree and stored using a pair of relations: nodes(id, type, label, value) child(child-id, parent-id)
Draw Data Matrix In Java
Using Barcode creator for Java Control to generate, create Data Matrix 2d barcode image in Java applications.
Creating Linear 1D Barcode In .NET
Using Barcode creator for ASP.NET Control to generate, create 1D image in ASP.NET applications.
Silberschatz Korth Sudarshan: Database System Concepts, Fourth Edition
III Object Based Databases and XML
10 XML
The McGraw Hill Companies, 2001
Storage of XML Data
Each element and attribute in the XML data is given a unique identi er A tuple inserted in the nodes relation for each element and attribute with its identi er (id), its type (attribute or element), the name of the element or attribute (label), and the text value of the element or attribute (value) The relation child is used to record the parent element of each element and attribute If order information of elements and attributes must be preserved, an extra attribute position can be added to the child relation to indicate the relative position of the child among the children of the parent As an exercise, you can represent the XML data of Figure 101 by using this technique This representation has the advantage that all XML information can be represented directly in relational form, and many XML queries can be translated into relational queries and executed inside the database system However, it has the drawback that each element gets broken up into many pieces, and a large number of joins are required to reassemble elements Map to relations In this approach, XML elements whose schema is known are mapped to relations and attributes Elements whose schema is unknown are stored as strings, or as a tree representation A relation is created for each element type whose schema is known All attributes of these elements are stored as attributes of the relation All subelements that occur at most once inside these element (as speci ed in the DTD) can also be represented as attributes of the relation; if the subelement can contain only text, the attribute stores the text value Otherwise, the relation corresponding to the subelement stores the contents of the subelement, along with an identi er for the parent type and the attribute stores the identi er of the subelement If the subelement has further nested subelements, the same procedure is applied to the subelement If a subelement can occur multiple times in an element, the map-to-relations approach stores the contents of the subelements in the relation corresponding to the subelement It gives both parent and subelement unique identi ers, and creates a separate relation, similar to the child relation we saw earlier in the tree representation, to identify which subelement occurs under which parent Note that when we apply this appoach to the DTD of the data in Figure 101, we get back the original relational schema that we have used in earlier chapters The bibliographical notes provide references to such hybrid approaches
Copyright © OnBarcode.com . All rights reserved.