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The Java Persistence API (JPA) : a standard interface-based Java model abstraction of persistence, developed by the JCP.

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/*
 * Copyright (c) 2008, 2009, 2011 Oracle, Inc. 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.
 */
package javax.persistence;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

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

/**
 * References name of a column in the SELECT clause of a SQL query - i.e., column alias, if applicable. Scalar
 * result types can be included in the query result by specifying this annotation in the metadata.
 *
 *  *
 * Example:
 *   Query q = em.createNativeQuery(
 *       "SELECT o.id AS order_id, " +
 *           "o.quantity AS order_quantity, " +
 *           "o.item AS order_item, " +
 *           "i.name AS item_name, " +
 *         "FROM Order o, Item i " +
 *         "WHERE (order_quantity > 25) AND (order_item = i.id)",
 *       "OrderResults");
 * 
 *   @SqlResultSetMapping(name="OrderResults",
 *       entities={
 *           @EntityResult(entityClass=com.acme.Order.class, fields={
 *               @FieldResult(name="id", column="order_id"),
 *               @FieldResult(name="quantity", column="order_quantity"),
 *               @FieldResult(name="item", column="order_item")})},
 *       columns={
 *           @ColumnResult(name="item_name")}
 *       )
 * 
 * @see SqlResultSetMapping
 * @since Java Persistence 1.0
 */
@Target({})
@Retention(RUNTIME)
public @interface ColumnResult
{

    /**
     * (Required) The name of a column in the SELECT clause of a SQL query
     * @return Name
     */
    String name();

    /**
     * (Optional) The Java type to which the column type is to be mapped.
     * @return type
     */
    Class type() default void.class;
}