Document Information


Part I Introduction

1.  Overview

2.  Using the Tutorial Examples

Part II The Web Tier

3.  Getting Started with Web Applications

4.  Java Servlet Technology

5.  JavaServer Pages Technology

6.  JavaServer Pages Documents

7.  JavaServer Pages Standard Tag Library

8.  Custom Tags in JSP Pages

9.  Scripting in JSP Pages

10.  JavaServer Faces Technology

11.  Using JavaServer Faces Technology in JSP Pages

12.  Developing with JavaServer Faces Technology

13.  Creating Custom UI Components

14.  Configuring JavaServer Faces Applications

15.  Internationalizing and Localizing Web Applications

Part III Web Services

16.  Building Web Services with JAX-WS

17.  Binding between XML Schema and Java Classes

18.  Streaming API for XML

19.  SOAP with Attachments API for Java

Part IV Enterprise Beans

20.  Enterprise Beans

21.  Getting Started with Enterprise Beans

22.  Session Bean Examples

23.  A Message-Driven Bean Example

Part V Persistence

24.  Introduction to the Java Persistence API

25.  Persistence in the Web Tier

26.  Persistence in the EJB Tier

Query Language Terminology

Simplified Query Language Syntax

Select Statements

Update and Delete Statements

Example Queries

Simple Queries

A Basic Select Query

Eliminating Duplicate Values

Using Named Parameters

Queries That Navigate to Related Entities

A Simple Query with Relationships

Navigating to Single-Valued Relationship Fields

Traversing Relationships with an Input Parameter

Traversing Multiple Relationships

Navigating According to Related Fields

Queries with Other Conditional Expressions

The LIKE Expression

The IS NULL Expression

The IS EMPTY Expression

The BETWEEN Expression

Comparison Operators

Bulk Updates and Deletes

Update Queries

Delete Queries

Full Query Language Syntax

BNF Symbols

BNF Grammar of the Java Persistence Query Language

FROM Clause


Identification Variables

Path Expressions

Examples of Path Expressions

Expression Types


WHERE Clause


Input Parameters

Conditional Expressions

Operators and Their Precedence

BETWEEN Expressions

IN Expressions

LIKE Expressions

NULL Comparison Expressions

Empty Collection Comparison Expressions

Collection Member Expressions


Functional Expressions

NULL Values

Equality Semantics


Return Types

The DISTINCT Keyword

Constructor Expressions


The GROUP BY Clause

The HAVING Clause

Part VI Services

28.  Introduction to Security in the Java EE Platform

29.  Securing Java EE Applications

30.  Securing Web Applications

31.  The Java Message Service API

32.  Java EE Examples Using the JMS API

33.  Transactions

34.  Resource Connections

35.  Connector Architecture

Part VII Case Studies

36.  The Coffee Break Application

37.  The Duke's Bank Application

Part VIII Appendixes

A.  Java Encoding Schemes

B.  About the Authors



Chapter 27

The Java Persistence Query Language

The Java Persistence query language defines queries for entities and their persistent state. The query language allows you to write portable queries that work regardless of the underlying data store.

The query language uses the abstract persistence schemas of entities, including their relationships, for its data model, and it defines operators and expressions based on this data model. The scope of a query spans the abstract schemas of related entities that are packaged in the same persistence unit. The query language uses a SQL-like syntax to select objects or values based on entity abstract schema types and relationships among them.

This chapter relies on the material presented in earlier chapters. For conceptual information, see Chapter 24, Introduction to the Java Persistence API. For code examples, see Chapters The persistence.xml File and Updating Data in the Database.