XQuery Terms

XQuery Terminology

Nodes

In XQuery, there are seven kinds of nodes: element, attribute, text, namespace, processing-instruction, comment, and document (root) nodes.

XML documents are treated as trees of nodes. The root of the tree is called the document node (or root node).

Look at the following XML document:

Example of nodes in the XML document above:

Atomic values

Atomic values are nodes with no children or parent.

Example of atomic values:

Items

Items are atomic values or nodes.

Relationship of Nodes

Parent

Each element and attribute has one parent.

In the following example; the book element is the parent of the title, author, year, and price:

Children

Element nodes may have zero, one or more children.

In the following example; the title, author, year, and price elements are all children of the book element:

Siblings

Nodes that have the same parent.

In the following example; the title, author, year, and price elements are all siblings:

Ancestors

A node's parent, parent's parent, etc.

In the following example; the ancestors of the title element are the book element and the bookstore element:

Descendants

A node's children, children's children, etc.

In the following example; descendants of the bookstore element are the book, title, author, year, and price elements: