src/javax/persistence/OrderColumn.java

/*******************************************************************************
 * 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 - Proposed Final Draft, Version 2.0 (August 31, 2009)
 *     Specification available from http://jcp.org/en/jsr/detail?id=317
 *
 * Java(TM) Persistence API, Version 2.0 - EARLY ACCESS
 * This is an implementation of an early-draft specification developed under the 
 * Java Community Process (JCP).  The code is untested and presumed not to be a  
 * compatible implementation of JSR 317: Java(TM) Persistence API, Version 2.0.   
 * We encourage you to migrate to an implementation of the Java(TM) Persistence 
 * API, Version 2.0 Specification that has been tested and verified to be compatible 
 * as soon as such an implementation is available, and we encourage you to retain 
 * this notice in any implementation of Java(TM) Persistence API, Version 2.0 
 * Specification that you distribute.
 ******************************************************************************/
package javax.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 a column that is used to maintain the persistent order of
 * a list. The persistence provider is responsible for maintaining the
 * order upon retrieval and in the database and for updating the
 * ordering upon flushing to the database to reflect any insertion,
 * deletion, or reordering affecting the list.
 *
 * <p> The <code>OrderColumn</code> annotation is specified on a
 * OneToMany or ManyToMany relationship or on an element
 * collection. The <code>OrderColumn</code> annotation is specified on
 * the side of the relationship that references the collection that is
 * to be ordered. The order column is not visible as part of the state
 * of the entity or embeddable class.
 *
 * <p> The {@link OrderBy} annotation
 * should be used for ordering that is visible as persistent state and
 * maintained by the application. The <code>OrderBy</code> annotation is not used
 * when <code>OrderColumn</code> is specified.
 * 
 * <pre>
 *
 *    Example:
 *
 *    &#064;Entity
 *    public class CreditCard {
 *
 *       &#064;Id long ccNumber;
 *
 *       &#064;OneToMany  // unidirectional
 *       &#064;OrderColumn
 *       List&#060;CardTransaction&#062; transactionHistory;
 *       ...
 *    }
 *
 * </pre>
 *
 * @see OrderBy
 *
 * @since Java Persistence 2.0
 */
@Target( { METHOD, FIELD })
@Retention(RUNTIME)
public @interface OrderColumn {

	/** (Optional) The name of the ordering column. 
         *  Defaults to the concatenation of the name of the 
         *  referencing property or field; "_"; "ORDER".
         */
	String name() default "";

	/** (Optional) Whether the database column is nullable. */
	boolean nullable() default true;

	/**
	 * (Optional) Whether the column is included in SQL INSERT statements
	 * generated by the persistence provider.
	 */
	boolean insertable() default true;

	/**
	 * (Optional) Whether the column is included in SQL UPDATE statements
	 * generated by the persistence provider.
	 */
	boolean updatable() default true;

	/**
	 * (Optional) The SQL fragment that is used when generating the DDL for the
	 * column.  Defaults to generated SQL to create a column of the inferred type.
	 */
	String columnDefinition() default "";
}