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XML Extender Administration and Programming


DTD reference table

The XML Extender also serves as an XML DTD repository. When a database is XML-enabled, a DTD reference table, DTD_REF, is created. Each row of this table represents a DTD with additional metadata information. Users can access this table, and insert their own DTDs. The DTDs in the DTD_REF table are used to validate XML documents and to help applications to define a DAD file. It has the schema name of db2xml. A DTD_REF table can have the columns shown in Table 50.


Table 50. DTD_REF table
Column name Data type Description
DTDID VARCHAR The primary key (unique and not NULL). It is used to identify the DTD. When it is specified in the DAD file, the DAD file must follow the schema that is defined by the DTD.
CONTENT XMLCLOB The content of the DTD.
USAGE_COUNT INTEGER The number of XML columns and XML collections in the database that use the DTD to define their DAD files.
AUTHOR VARCHAR The author of the DTD, optional `information for the user to input.
CREATOR VARCHAR The user ID that does the first insertion. The CREATOR column is optional.
UPDATOR VARCHAR The user ID that does the last update. The UPDATOR column is optional.

Restriction: The DTD can be modified by the application only when the USAGE_COUNT is zero.


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