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SAP Sybase SQL Anywhere 16.0 » SQL Anywhere Server - SQL Usage » XML in the database

 

Storage of XML documents in relational databases

SQL Anywhere supports two data types that can be used to store XML documents in your database: the XML data type and the LONG VARCHAR data type. Both of these data types store the XML document as a string in the database.

The XML data type uses the character set encoding of the database server. The XML encoding attribute should match the encoding used by the database server. The XML encoding attribute does not specify how the automatic character set conversion is completed.

You can cast between the XML data type and any other data type that can be cast to or from a string. There is no checking that the string is well formed when it is cast to XML.

When you generate elements from relational data, any characters that are invalid in XML are escaped unless the data is of type XML. For example, suppose you want to generate a <product> element with the following content so that the element content contains less than and greater than signs:

<hat>bowler</hat>

If you write a query that specifies that the element content is of type XML, then the greater than and less than signs are not quoted, as follows:

SELECT XMLFOREST( CAST( '<hat>bowler</hat>' AS XML ) AS product );

You get the following result:

<product><hat>bowler</hat></product>

However, if the query does not specify that the element content is of type XML, for example:

SELECT XMLFOREST( '<hat>bowler</hat>' AS product );

In this case, the less than and greater than signs are replaced with entity references as follows:

<product>&lt;hat&gt;bowler&lt;/hat&gt;</product>

Attributes are always quoted, regardless of the data type.

 See also