XQuery by Walmsley, Priscilla -- Read -- Imperial Library of Trantor

Index

Preface

Contents of This Book Reading the Syntax Diagrams Conventions Used in This Book Using Code Examples Useful Functions Safari® Books Online We’d Like to Hear from You Acknowledgments

1. Introduction to XQuery

What Is XQuery?

Capabilities of XQuery Uses for XQuery Processing Scenarios

Easing into XQuery Path Expressions FLWORs Adding XML Elements and Attributes

Adding Elements Adding Attributes

Functions Joins Aggregating and Grouping Values

2. XQuery Foundations

The Design and History of the XQuery Language XQuery in Context

XQuery and XPath XQuery Versus XSLT XQuery Versus SQL XQuery and XML Schema

Processing Queries

Input Documents The Query The Context The Query Processor The Results of the Query

The XQuery Data Model

Nodes

Node kinds The node hierarchy The node family Roots, documents, and elements Node identity and name String and typed values of nodes

Atomic Values Sequences

Types Namespaces

3. Expressions: XQuery Building Blocks

Categories of Expressions Keywords and Names Whitespace in Queries Literals Variables Function Calls Comments Precedence and Parentheses Comparison Expressions

General Comparisons

General comparisons on multi-item sequences General comparisons and types

Value Comparisons Node Comparisons

Conditional (if-then-else) Expressions

Conditional Expressions and Effective Boolean Value Nesting Conditional Expressions

Switch Expressions Logical (and/or) Expressions

Precedence of Logical Expressions Negating a Boolean Value

4. Navigating XML by Using Paths

Path Expressions

Path Expressions and Context

Steps and changing context

Steps Axes Node Tests

Node name tests Node name tests and namespaces Node name tests and wildcards Node kind tests

Abbreviated Syntax Other Expressions as Steps

Predicates

Comparisons in Predicates Using Positions in Predicates

Understanding positional predicates The position and last functions Positional predicates and reverse axes

Using Multiple Predicates More Complex Predicates

A Closer Look at Context

Working with the Context Node Accessing the Root

Dynamic Paths The Simple Map Operator

5. Adding Elements and Attributes to Results

Including Elements and Attributes from the Input Document Direct Element Constructors

Containing Literal Characters Containing Other Element Constructors Containing Enclosed Expressions

Enclosed expressions that evaluate to elements Enclosed expressions that evaluate to attributes Enclosed expressions that evaluate to atomic values Enclosed expressions with multiple sub-expressions

Specifying Attributes Directly Declaring Namespaces in Direct Constructors Use Case: Modifying an Element from the Input Document Direct Element Constructors and Whitespace

Boundary whitespace The boundary-space declaration Forcing boundary whitespace preservation

Computed Constructors

Computed Element Constructors

Names of computed element constructors Content of computed element constructors

Computed Attribute Constructors Use Case: Turning Content to Markup

6. Selecting and Joining Using FLWORs

Selecting with Path Expressions FLWOR Expressions

The for Clause

Range expressions Multiple for clauses

The let Clause The where Clause The return Clause The Scope of Variables

Quantified Expressions

Binding Multiple Variables

Selecting Distinct Values Joins

Three-Way Joins Outer Joins

Outer joins with allowing empty

Joins and Types

7. Sorting and Grouping

Sorting in XQuery

The order by Clause

Using multiple ordering specifications Sorting and types Order modifiers Empty order Stable ordering More complex order specifications

The sort Function Document Order

Document order defined Sorting in document order Inadvertent re-sorting in document order

Document Order Comparisons Reversing the Order Indicating That Order Is Not Significant

The unordered function The unordered expression The ordering mode declaration

Grouping

Grouping Using the group by Clause

Grouping on multiple values More complex grouping specifications

Aggregating Values

Ignoring “Missing” Values Counting “Missing” Values Aggregating on Multiple Values Constraining and Sorting on Aggregated Values

8. Functions

Built-in Versus User-Defined Functions Calling Functions

Function Names Function Signatures Argument Lists

Argument lists and the empty sequence Argument lists and sequences

Sequence Types Calling Functions with the Arrow Operator

User-Defined Functions

Why Define Your Own Functions? Function Declarations The Function Body The Function Name The Parameter List

Accepting arguments that are nodes versus atomic values Accepting arguments that are the empty sequence

Functions and Context Recursive Functions

9. Advanced Queries

Working with Positions and Sequence Numbers

Adding Sequence Numbers to Results Using the count Clause Testing for the Last Item

Windowing

Using start and end Conditions Windows Based on Position Windows Based on Previous or Next Items Sliding Windows

Copying Input Elements with Modifications

Adding Attributes to an Element Removing Attributes from an Element Removing Attributes from All Descendants Removing Child Elements Changing Names

Combining Results

Sequence Constructors The union Expression The intersect Expression The except Expression

Using Intermediate XML Documents

Creating Lookup Tables Reducing Complexity

10. Namespaces and XQuery

XML Namespaces

Namespace URIs Declaring Namespaces Default Namespace Declarations Namespaces and Attributes Namespace Declarations and Scope

Namespaces and XQuery Namespace Declarations in Queries

Predeclared Namespaces Prolog Namespace Declarations

Default namespace declarations in the prolog The default function namespace declaration Other prolog namespace declarations

Namespace Declarations in Direct Element Constructors Namespace Declarations in Computed Constructors The Impact and Scope of Namespace Declarations

Scope of namespace declarations Names affected by namespace declarations Namespace declarations and input elements

Controlling Namespace Declarations in Your Results

In-Scope Versus Statically Known Namespaces Controlling the Copying of Namespace Declarations

URI-Qualified Names

11. A Closer Look at Types

The XQuery Type System

Advantages of a Strong Type System Do You Need to Care About Types?

The Built-in Types

Atomic Types List Types Union Types

Types, Nodes, and Atomic Values

Nodes and Types Atomic Values and Types

Type Checking in XQuery

The Static Analysis Phase The Dynamic Evaluation Phase

Automatic Type Conversions

Subtype Substitution Type Promotion Casting of Untyped Values Atomization Effective Boolean Value Function Conversion Rules

Sequence Types

Occurrence Indicators Generic Sequence Types Simple Type Names as Sequence Types Element and Attribute Tests Sequence Type Matching The instance of Expression

Constructors and Casting

Constructors The Cast Expression The Castable Expression Casting Rules

Casting among the primitive types Casting from xs:string or xs:untypedAtomic Casting to xs:string or xs:untypedAtomic Casting among derived types

12. Prologs, Modules, and Variables

Structure of a Query: Prolog and Body

Prolog Declarations The Version Declaration

Assembling Queries from Multiple Modules

Library Modules Importing a Library Module

Multiple module imports Multi-level imports

Loading a Library Module Dynamically

Variable Declarations

Variable Declaration Syntax The Scope of Variables Variable Names Initializing Expressions External Variables

Private Functions and Variables Declaring External Functions

13. Inputs and Outputs

Types of Input and Output Documents Accessing Input Documents

Accessing a Single Document with a Function

Resolving URIs of input documents

Accessing a Collection Setting the Context Outside the Query Using Variables Setting the Context in the Prolog

Serializing Output

Serialization Methods Serialization Parameters Specifying Serialization Parameters by Using Option Declarations Specifying Serialization Parameters by Using a Separate XML Document Serialization Errors Serializing to a String

14. Using Schemas with XQuery

What Is a Schema? Why Use Schemas with Queries? W3C XML Schema: A Brief Overview

Element and Attribute Declarations Types

Simple and complex types User-defined types List types

Namespaces and XML Schema

In-Scope Schema Definitions

Where Do In-Scope Schema Definitions Come From? Schema Imports

Importing a schema with no target namespace Importing multiple schemas with the same target namespace Schema imports and library modules

Schema Validation and Type Assignment

The Validate Expression Validation Mode Assigning Type Annotations to Nodes Nodes and Typed Values Types and Newly Constructed Elements and Attributes

Sequence Types and Schemas

15. Static Typing

What Is Static Typing?

Obvious Static Type Errors Static Typing and Schemas Raising “False” Errors Static Typing Expressions and Constructs

The Typeswitch Expression The Treat Expression Type Declarations

Type Declarations in FLWORs Type Declarations in Quantified Expressions Type Declarations in Global Variable Declarations

The zero-or-one, one-or-more, and exactly-one Functions

16. Writing Better Queries

Query Design Goals Clarity

Improving the Layout Choosing Names Using Comments for Documentation

Modularity Robustness

Handling Data Variations Handling Missing Values

Absent values Empty and nil values Default “missing” values

Error Handling

Avoiding Dynamic Errors The error and trace Functions Try/Catch Expressions

Performance

Avoid Reevaluating the Same or Similar Expressions Avoid Unnecessary Sorting Avoid Expensive Path Expressions Use Predicates Instead of where Clauses

17. Working with Numbers

The Numeric Types

The xs:decimal Type The xs:integer Type The xs:float and xs:double Types The xs:numeric Type

Constructing Numeric Values

The number Function Numeric Type Promotion

Comparing Numeric Values Arithmetic Operations

Arithmetic Operations on Multiple Values Arithmetic Operations and Types Precedence of Arithmetic Operators Addition, Subtraction, and Multiplication Division Modulus (Remainder)

Functions on Numbers Formatting Numbers

Formatting Integers Formatting Decimal Numbers The Decimal Format Declaration

18. Working with Strings

The xs:string Type Constructing Strings

String Literals The xs:string Constructor and the string Function

Comparing Strings

Comparing Entire Strings Determining Whether a String Contains Another String Matching a String to a Pattern

Substrings Finding the Length of a String Concatenating and Splitting Strings

Concatenating Strings Splitting Strings Apart Converting Between Codepoints and Strings

Manipulating Strings

Converting Between Uppercase and Lowercase Replacing Individual Characters in Strings Replacing Substrings That Match a Pattern

Whitespace and Strings

Normalizing Whitespace

Internationalization Considerations

Collations

Supported collations Specifying a collation

Unicode Normalization Determining the Language of an Element

19. Regular Expressions

The Structure of a Regular Expression

Atoms Quantifiers Parenthesized Sub-Expressions and Branches

Representing Individual Characters Representing Any Character Representing Groups of Characters

Multi-Character Escapes Category Escapes Block Escapes

Character Class Expressions

Single Characters and Ranges Subtraction from a Range Negative Character Class Expressions Escaping Rules for Character Class Expressions

Reluctant Quantifiers Anchors Back-References Using Flags Using Sub-Expressions with Replacement Variables

20. Working with Dates, Times, and Durations

The Date and Time Types

Constructing and Casting Dates and Times Time Zones

Explicit versus implicit time zones Adjusting time zones Finding the time zone of a value

Comparing Dates and Times

The Duration Types

The xs:yearMonthDuration and xs:dayTimeDuration Types Comparing Durations

Extracting Components of Dates, Times, and Durations Formatting Dates and Times Using Arithmetic Operators on Dates, Times, and Durations

Subtracting Dates and Times Adding and Subtracting Durations from Dates and Times Adding and Subtracting Two Durations Multiplying and Dividing Durations by Numbers Dividing Durations by Durations

The Date Component Types

21. Working with Qualified Names, URIs, and IDs

Working with Qualified Names

Retrieving Node Names Constructing Qualified Names Other Name-Related Functions

Working with URIs

Base and Relative URIs

Using the xml:base attribute Finding the base URI of a node Resolving URIs Static base URI

Documents and URIs

Finding the URI of a document Opening a document from a dynamic value

Escaping URIs

Working with IDs

Joining IDs and IDREFs Constructing ID Attributes Generating Unique ID Values

22. Working with Other XML Constructs

XML Comments

XML Comments and the Data Model Querying Comments Comments and Sequence Types Constructing Comments

Processing Instructions

Processing Instructions and the Data Model Querying Processing Instructions Processing Instructions and Sequence Types Constructing Processing Instructions

Documents

Document Nodes and the Data Model Document Nodes and Sequence Types Constructing Document Nodes

Text Nodes

Text Nodes and the Data Model Querying Text Nodes Text Nodes and Sequence Types Why Work with Text Nodes? Constructing Text Nodes

XML Entity and Character References CDATA Sections

23. Function Items and Higher-Order Functions

Why Higher-Order Functions? Constructing Functions and Calling Them Dynamically

Named Function References Using function-lookup to Obtain a Function Inline Function Expressions Partial Function Application The Arrow Operator and Dynamic Function Calls Syntax Recap

Functions and Sequence Types Higher-Order Functions

Built-In Higher-Order Functions Writing Your Own Higher-Order Functions

24. Maps, Arrays, and JSON

Maps

Constructing Maps

Using a map constructor Using map:entry and map:merge to create maps

Looking Up Map Values

Using the map:get function Invoking maps as functions Using the lookup operator on maps

Querying Maps Changing Maps Iterating over Entries in a Map Maps and Sequence Types

Arrays

Constructing Arrays Arrays Versus Sequences Arrays and Atomization Looking Up Array Values

Using the array:get function Invoking arrays as functions Using the lookup operator on arrays

Querying Arrays Changing Arrays Arrays and Sequence Types

JSON

Parsing JSON Serializing JSON Converting Between JSON and XML

25. Implementation-Specific Features

Conformance Version Support

New Features in XQuery 3.0 New Features in XQuery 3.1

Setting the Query Context The Option Declaration Extension Expressions Annotations

26. XQuery for SQL Users

Relational Versus XML Data Models Comparing SQL Syntax with XQuery Syntax

A Simple Query Conditions and Operators

Comparisons Arithmetic operators Boolean operators

Functions Selecting Distinct Values Working with Multiple Tables and Subqueries

Subselects Combining queries by using set operators

Grouping

Combining SQL and XQuery

Combining Structured and Semi-Structured Data Flexible Data Structures

SQL/XML

27. XQuery for XSLT Users

XQuery and XPath XQuery Versus XSLT

Shared Components Equivalent Components Differences

Paradigm differences: push versus pull Optimization for particular use cases Convenient features of XSLT

Using XQuery and XSLT Together XQuery Backward Compatibility with XPath 1.0

Data Model New Expressions Path Expressions Function Conversion Rules Arithmetic and Comparison Expressions Built-in Functions

28. Additional XQuery-Related Standards

XQuery Update Facility Full-Text Search XQueryX RESTXQ XQuery API for Java (XQJ)

A. Built-in Function Reference B. Built-in Types

xs:anyAtomicType xs:anySimpleType xs:anyType xs:anyURI

Casting and Comparing xs:anyURI Values

xs:base64Binary xs:boolean

Constructing xs:boolean Values Casting xs:boolean Values

xs:byte xs:date xs:dateTime xs:dateTimeStamp xs:dayTimeDuration xs:decimal

Casting xs:decimal Values

xs:double

Casting xs:double Values

xs:duration xs:ENTITIES xs:ENTITY xs:error xs:float

Casting xs:float Values

xs:gDay xs:gMonth xs:gMonthDay xs:gYear xs:gYearMonth xs:hexBinary xs:ID xs:IDREF xs:IDREFS xs:int xs:integer

Casting xs:integer Values

xs:language xs:long xs:Name xs:NCName xs:negativeInteger xs:NMTOKEN xs:NMTOKENS xs:nonNegativeInteger xs:nonPositiveInteger xs:normalizedString xs:NOTATION xs:numeric xs:positiveInteger xs:QName xs:short xs:string xs:time xs:token xs:unsignedByte xs:unsignedInt xs:unsignedLong xs:unsignedShort xs:untyped xs:untypedAtomic xs:yearMonthDuration

C. Error Summary

FOAP0001 FOAR0001 FOAR0002 FOAY0001 FOAY0002 FOCA0001 FOCA0002 FOCA0003 FOCA0005 FOCA0006 FOCH0001 FOCH0002 FOCH0003 FOCH0004 FODC0001 FODC0002 FODC0003 FODC0004 FODC0005 FODC0006 FODC0010 FODF1280 FODF1310 FODT0001 FODT0002 FODT0003 FOER0000 FOFD1340 FOFD1350 FOJS0001 FOJS0003 FOJS0004 FOJS0005 FOJS0006 FOJS0007 FONS0004 FONS0005 FOQM0001 FOQM0002 FOQM0003 FOQM0004 FOQM0005 FOQM0006 FORG0001 FORG0002 FORG0003 FORG0004 FORG0005 FORG0006 FORG0008 FORG0009 FORG0010 FORX0001 FORX0002 FORX0003 FORX0004 FOTY0012 FOTY0013 FOTY0014 FOTY0015 FOUT1170 FOUT1190 FOUT1200 FOXT0001 FOXT0002 FOXT0003 FOXT0004 SENR0001 SEPM0004 SEPM0009 SEPM0010 SEPM0016 SEPM0017 SEPM0018 SEPM0019 SERE0003 SERE0005 SERE0006 SERE0008 SERE0012 SERE0014 SERE0015 SERE0020 SERE0021 SERE0022 SERE0023 SESU0007 SESU0011 SESU0013 XPDY0002 XPDY0050 XPDY0130 XPST0001 XPST0003 XPST0005 XPST0008 XPST0017 XPST0051 XPST0080 XPST0081 XPTY0004 XPTY0018 XPTY0019 XPTY0020 XPTY0117 XQDY0025 XQDY0026 XQDY0027 XQDY0041 XQDY0044 XQDY0054 XQDY0061 XQDY0064 XQDY0072 XQDY0074 XQDY0084 XQDY0091 XQDY0092 XQDY0096 XQDY0101 XQDY0102 XQDY0137 XQST0009 XQST0012 XQST0013 XQST0016 XQST0022 XQST0031 XQST0032 XQST0033 XQST0034 XQST0035 XQST0038 XQST0039 XQST0040 XQST0045 XQST0046 XQST0047 XQST0048 XQST0049 XQST0052 XQST0055 XQST0057 XQST0058 XQST0059 XQST0060 XQST0065 XQST0066 XQST0067 XQST0068 XQST0069 XQST0070 XQST0071 XQST0075 XQST0076 XQST0079 XQST0085 XQST0087 XQST0088 XQST0089 XQST0090 XQST0094 XQST0097 XQST0098 XQST0099 XQST0103 XQST0104 XQST0106 XQST0108 XQST0109 XQST0110 XQST0111 XQST0113 XQST0114 XQST0115 XQST0116 XQST0118 XQST0119 XQST0125 XQST0129 XQST0134 XQTY0024 XQTY0030 XQTY0086 XQTY0105

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