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XML Databases - Coggle Diagram

- - - - shipping, carriers of goods and customs and tax officials
      - Online marketplace
      - chemical industry
- - - - has many of the drawbacks
        
        lacks atomicity
        
        lacks data isolation
        
        lacks concurrent access
        
        lacks security.
  - - - Small XML documents can be stored as string (clob) values in tuples in a relational database
      - Oracle, support function indices that can help avoid replication of attributes between the XML string and relation attributes.
    - - Information can be represented directly in relational format and many XML queries can be translated into relational queries and run on database systems.
    - - , XML elements whose schema is known are mapped to relations
        and attributes.
    - - mapping used for publishing data may be simple or
        complex.
      - complicated mapping would allow nested structures to be created.
    - - Several database systems provide native support for XML data.
- - - - XQuery queries are modeled after SQL queries
      - For clause is like the from clause of SQL
      - Let clause simply allows the results of XPath expressions to be assigned to variable names for simplicity of representation
      - Where and Order clause are like the ones from SQL
      - return clause allows the construction of results in XML
    - - Joins are specified in XQuery much as they are inSQL.
    - - FLWOR expressions can be nested inside the return clause, to generate nests of elements that do not appear in the source document.
    - - Results can be sorted by using the order by clause
    - - provides a variety of built-in functions, such as numeric functions and string matching and manipulation functions.
      - XQuery performs type conversion automatically whenever required.
    - - if-then-else
      - The XQJ standard provides an API for sending XQuery queries to an XML database system and retrieving XML results. Its functionality is similar to the JDBC API.
- - - - Individual text elements and attributes cannot be typed further
      - Difficult to use the DTD mechanism to specify unordered sets of subelements.
      - Lack of typing in IDs and IDREFSs.
  - - - Allows you to limit the text displayed on elements to specific types
      - allows user-defined types to be created.
      - allows uniqueness and foreign-key constraints
      - It integrates with namespaces to allow different parts of a document to conform to different schemas.
      - allows complex types to be extended using a form of inheritance.
      - Allows types to be constrained to create specialized types, for example by specifying minimum and maximum values.
- - - - Provides functions for updating the document by adding and deleting attribute and element children of a node, setting node values.
      - can be used to access XML data stored in databases
    - - built on the notion of event handlers
      - requires more programming effort than the DOM, but helps avoid the effort of creating a DOM tree in situations where the application needs to create its own data representation.