science

XQuery Update Facility

XQuery Update Facility is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand XQuery Update Facility rather than just read about it. In short: XQuery Update Facility is an extension to the XML Query language, XQuery. It provides expressions that can be used to make changes to instances of the XQuery 1.0 and XPath 2.0 Data Model.

Key takeaways

XQuery Update Facility belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect XQuery Update Facility to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of XQuery Update Facility from memory before moving on to harder problems.

Reference excerpt

XQuery Update Facility is an extension to the XML Query language, XQuery. It provides expressions that can be used to make changes to instances of the XQuery 1.0 and XPath 2.0 Data Model. It became a W3C Candidate Recommendation on 31 July 2009 and was finalised as Recommendation on 17 March 2011. A version to work with XQuery 3.0 was drafted, but was never completed, and is archived as a W3C Working Group Note.

Implementations

BaseX - An open source XML Database and XQuery Processor; supported since Version 6.0 DataDirect XQuery - a java-based commercial XQuery processor. Supported since Version 4.0 EMC Documentum xDB - Native XML Database. XQuery Update Facility supported since Version 9.0 eXist - The open source XML Database provide an extension to XQuery, which maps each of the XUpdate instructions to a corresponding XQuery expression MonetDB/XQuery - An open source XQuery processor on top of the MonetDB relational database system (declared obsolete since 2011). PureXML - IBM DB2 offers XQuery Update Facility since Version 9.5. Oracle XMLDB - Oracle database offers XQuery Update Facility since version 12.1.0.2 ). qizxopen XQuery engine. SaxonSA XSLT and XQuery Processor - by Michael Kay; Supported since Version 9.1, but only in the commercial version. XQilla - An open source (ASL2.0) XQuery processing library with support for the latest XQuery Update features. XQilla is written in C++ and includes a command line executable shell to execute queries against XML content stored on a local filesystem. This library is actively developed and part of a supported Oracle product, Berkeley DB XML.

References

External links XQuery Updates at Wikibooks XQuery Update Facility on W3 XQuery Update for the impatient, a tutorial on XQuery Update and its quirks. XQuery Update Facility - Changes in Oracle Database 12c Release 1 (12.1.0.1) for Oracle XML DB.

Worked examples

Example 1 — a first encounter with XQuery Update Facility

Start with the simplest possible case. Write down what XQuery Update Facility claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to XQuery Update Facility before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about XQuery Update Facility ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of XQuery Update Facility

In research: XQuery Update Facility appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses XQuery Update Facility in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: XQuery Update Facility is common in secondary-school and first-year university syllabi. It links to neighbouring topics Standards and measurement stubs, World Wide Web Consortium standards, so understanding it makes those chapters shorter.
In everyday life: Look for XQuery Update Facility outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study XQuery Update Facility in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what XQuery Update Facility means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain XQuery Update Facility out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is XQuery Update Facility in simple terms?

XQuery Update Facility is an extension to the XML Query language, XQuery. It provides expressions that can be used to make changes to instances of the XQuery 1.0 and XPath 2.0 Data Model.

Why does XQuery Update Facility matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study XQuery Update Facility?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on XQuery Update Facility.