PostgreSQL – XMLELEMENT Function

The xmlelement function in PostgreSQL is used to create an XML element. It allows you to construct an XML element with a specified name and content, which can include nested elements, attributes, and text values. Below is the basic syntax of the xmlelement function:

xmlelement [ ( name [ , xml_attributes [ , content ] ] ) ]

where name is the name of the XML element you want to create. It can be a string or an expression that evaluates to a string.

and xml_attributes is an optional argument that allows you to specify attributes for the XML element. This can be a list of attribute-value pairs.

and content is an optional argument that specifies the content of the XML element. This can include nested elements, text values, or other XML fragments.

Here’s an example of using the xmlelement function to create a simple XML element:

SELECT xmlelement(name "person", 'John Doe');

This query creates an XML element <person> with the text content ‘John Doe’.

You can also use the xmlelement function to create more complex XML structures with nested elements and attributes. For example:

SELECT xmlelement( name "book", xmlattributes( 'ISBN-12345' AS "isbn", 'Science Fiction' AS "genre" ), xmlelement(name "title", 'The Hitchhiker''s Guide to the Galaxy'), xmlelement(name "author", 'Douglas Adams') );

In this example, we create an XML element <book> with attributes isbn and genre, and it contains nested <title> and <author> elements.

The xmlelement function is a powerful tool for generating XML documents or fragments within your PostgreSQL queries, and it can be used in various ways to suit your XML construction needs.