Despite the excitement surrounding XML, it is important to note that most operational business data, even for new Web-based applications, continues to be stored in relational DBMSs. This is unlikely to change in the foreseeable future because of their reliability, scalability, tools, and performance. Consequently, if XML is to fulfil its potential, some mechanism is required to publish relational data in the form of XML documents. The SQL:2003 standard has defined extensions to SQL to enable the publication of XML, commonly referred to as SQL/XML. Discuss in detail these extensions.

Question

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The Answer is SQL/XML contains:
• a new native XML data type, XML, which allows XML documents to be treated as relational values in columns of tables, attributes in user-defined types, variables, and parameters to functions;
• a set of operators for the type:
▪ XMLELEMENT, to generate an XML value with a single element as a child of its root item. The element can have zero or more attributes specified using an XMLATTRIBUTES subclause.
▪ XMLFOREST, to generate an XML value with a list of elements as children of a root item.
▪ XMLCONCAT, to concatenate a list of XML values.
▪ XMLPARSE, to perform a non-validating parse of a character string to produce an XML value.
▪ XMLROOT, to create an XML value by modifying the properties of the root item of another XML value.
▪ XMLCOMMENT, to generate an XML comment.
▪ XMLPI, to generate an XML processing instruction.
▪ XMLSERIALIZE, to generate a character or binary string from an XML value;
▪ XMLAGG, an aggregate function, to generate a forest of elements from a collection of elements.
• an implicit set of mappings from relational data to XML. The mapping may take as its source an individual table, all the tables in a particular schema, or all the tables in a given catalog. The standard does not specify a syntax for the mapping; instead it is provided for use by applications and as a reference for other standards. The mapping produces two XML documents: one that contains the mapped table data and the other that contains an XML Schema describing the first document.

Despite the Excitement Surrounding XML, It Is Important to Note