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/*
 * Copyright (c) 2008, 2023 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     Linda DeMichiel - 2.1
//     Linda DeMichiel - 2.0

package jakarta.persistence;

import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Specifies the ordering of the elements of a collection-valued
 * association or element collection at the point when the association
 * or collection is retrieved.
 * 
 * 

The syntax of the {@code value} ordering element is an * {@code orderby_list}, as follows: * * {@snippet : * orderby_list ::= orderby_item [, orderby_item]* * orderby_item ::= [property_or_field_name] [ASC | DESC] * } * *

If {@code ASC} or {@code DESC} is not specified, {@code ASC} * (ascending order) is assumed. * *

If the ordering element is not specified for an entity association, * ordering by the primary key of the associated entity is assumed. * *

The property or field name must correspond to that of a persistent * property or field of the associated class or embedded class within it. * The properties or fields used in the ordering must correspond to columns * for which comparison operators are supported. * *

The dot ({@code .}) notation is used to refer to an attribute within * an embedded attribute. The value of each identifier used with the dot * notation is the name of the respective embedded field or property. * *

The {@code OrderBy} annotation may be applied to an element * collection. When {@code OrderBy} is applied to an element collection * of basic type, the ordering is by value of the basic objects and the * property or field name is not used. When specifying an ordering over * an element collection of embeddable type, the dot notation must be * used to specify the attribute or attributes that determine the ordering. * *

The {@code OrderBy} annotation is not used when an order column is * specified using {@link OrderColumn}. * * *

Example 1: * {@snippet : * @Entity * public class Course { * ... * @ManyToMany * @OrderBy("lastname ASC") * public List getStudents() { ... } * ... * } * } * *

Example 2: * {@snippet : * @Entity * public class Student { * ... * @ManyToMany(mappedBy = "students") * @OrderBy // ordering by primary key is assumed * public List getCourses() { ... } * ... * } * } * *

Example 3: * {@snippet : * @Entity * public class Person { * ... * @ElementCollection * @OrderBy("zipcode.zip, zipcode.plusFour") * public Set

getResidences() { ... } * ... * } * * @Embeddable * public class Address { * protected String street; * protected String city; * protected String state; * @Embedded * protected Zipcode zipcode; * } * * @Embeddable * public class Zipcode { * protected String zip; * protected String plusFour; * } * } * * @see OrderColumn * * @since 1.0 */ @Target({METHOD, FIELD}) @Retention(RUNTIME) public @interface OrderBy { /** * An {@code orderby_list}. Specified as follows: * * {@snippet : * orderby_list::= orderby_item [,orderby_item]* * orderby_item::= [property_or_field_name] [ASC | DESC] * } * *

If {@code ASC} or {@code DESC} is not specified, * {@code ASC} (ascending order) is assumed. * *

If the ordering element is not specified, ordering by * the primary key of the associated entity is assumed. */ String value() default ""; }





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