/*
 * Copyright (c) 2008, 2009 Sun Microsystems. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Linda DeMichiel - Java Persistence 2.0 - Version 2.0 (October 1, 2009)
 *     Specification available from http://jcp.org/en/jsr/detail?id=317
 */

// $Id: EntityResult.java 20957 2011-06-13 09:58:51Z stliu $

package javax.persistence;

import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Used to map the SELECT clause of a SQL query to an entity result.
 * If this annotation is used, the SQL statement should select
 * all of the columns that are mapped to the entity object.
 * This should include foreign key columns to related entities.
 * The results obtained when insufficient data is available
 * are undefined.
 *
 * <pre>
 *   Example:
 *
 *   Query q = em.createNativeQuery(
 *       "SELECT o.id, o.quantity, o.item, i.id, i.name, i.description "+
 *           "FROM Order o, Item i " +
 *           "WHERE (o.quantity > 25) AND (o.item = i.id)",
 *       "OrderItemResults");
 *   @SqlResultSetMapping(name="OrderItemResults",
 *       entities={
 *           @EntityResult(entityClass=com.acme.Order.class),
 *           @EntityResult(entityClass=com.acme.Item.class)
 *   })
 * </pre>
 *
 * @see SqlResultSetMapping
 *
 * @since Java Persistence 1.0
 */
@Target({})
@Retention(RUNTIME)
public @interface EntityResult {

    /** The class of the result. */
    Class entityClass();

    /**
     * Maps the columns specified in the SELECT list of the
     * query to the properties or fields of the entity class.
     */
    FieldResult[] fields() default {};

    /**
     * Specifies the column name (or alias) of the column in
     * the SELECT list that is used to determine the type of
     * the entity instance.
     */
    String discriminatorColumn() default "";
}