/*
 * 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.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

Specifies that a unique constraint is to be included in
the generated DDL for a primary or secondary table.

   Example:
   @Entity
   @Table(
       name="EMPLOYEE",
       uniqueConstraints=
           @UniqueConstraint(columnNames={"EMP_ID", "EMP_NAME"})
   )
   public class Employee { ... }

Since:
Java Persistence 1.0/**
 * Specifies that a unique constraint is to be included in
 * the generated DDL for a primary or secondary table.
 * <p>
 * <pre>
 *    Example:
 *    &#064;Entity
 *    &#064;Table(
 *        name="EMPLOYEE",
 *        uniqueConstraints=
 *            &#064;UniqueConstraint(columnNames={"EMP_ID", "EMP_NAME"})
 *    )
 *    public class Employee { ... }
 * </pre>
 *
 * @since Java Persistence 1.0
 */
@Target({TYPE})
@Retention(RUNTIME)
public @interface UniqueConstraint {
  
(Optional) Constraint name.  A provider-chosen name will be chosen
if a name is not specified.
Returns:
name
Since:
Java Persistence 2.0/**
   * (Optional) Constraint name.  A provider-chosen name will be chosen
   * if a name is not specified.
   *
   * @return name
   * @since Java Persistence 2.0
   */
  String name() default "";

  
(Required) An array of the column names that make up the constraint.
Returns:
col names/**
   * (Required) An array of the column names that make up the constraint.
   *
   * @return col names
   */
  String[] columnNames();
}