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xmlattr

1. XMLATTR Function​

The XMLATTR function in H2 database is used to extract the value of an attribute from an XML element.

2. Syntax​

The syntax for the XMLATTR function in H2 database is as follows:

XMLATTR(xml, attribute)

Arguments​

  • xml: The XML element from which the attribute value needs to be extracted. It should be a valid XML string.
  • attribute: The name of the attribute whose value needs to be extracted. It should be a string.

Return​

  • The XMLATTR function returns the value of the specified attribute as a string.

3. Notes​

  • The XMLATTR function in H2 database works only with valid XML strings. If the input xml is not well-formed, the function will return NULL.
  • If the given attribute is not present in the XML element, the function will return NULL.
  • The XMLATTR function is case-sensitive when it comes to attribute names.

4. Examples​

Here are a few examples demonstrating the usage of the XMLATTR function in H2 database:

Example 1 - Extracting the value of the "name" attribute from an XML element:​

SELECT XMLATTR('<person name="John" age="30" />', 'name') AS attribute_value;

Output:

attribute_value
---------------
John

Example 2 - Extracting the value of an attribute from XML elements stored in a column:​

CREATE TABLE xml_data (
  id INT PRIMARY KEY,
  xml_element XML
);

INSERT INTO xml_data VALUES (1, '<book title="The Great Gatsby" author="F. Scott Fitzgerald" />'),
                            (2, '<book title="To Kill a Mockingbird" author="Harper Lee" />');

SELECT id, XMLATTR(xml_element, 'title') AS title, XMLATTR(xml_element, 'author') AS author
FROM xml_data;

Output:

id |         title          |       author
---+------------------------+-------------------
1  | The Great Gatsby       | F. Scott Fitzgerald
2  | To Kill a Mockingbird  | Harper Lee
  • xmlnode - Extract XML element as a string
  • XMLEXISTS - Check if an XML element exists