package org.apache.torque.engine.database.model;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE

  * file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the

  * License. You may obtain a copy of the License at

  * 

  * http://www.apache.org/licenses/LICENSE-2.0

  * 

  * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on

  * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the

  * specific language governing permissions and limitations under the License.

  */

 import java.util.List;

 /**

  * Information about unique columns of a table. This class assumes that in the underlying RDBMS, unique constraints and

  * unique indices are roughly equivalent. For example, adding a unique constraint to a column also creates an index on

  * that column (this is known to be true for MySQL and Oracle).

  * 

  * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>

  * @author <a href="mailto:dlr@collab.net">Daniel Rall</a>

  * @version $Id: Unique.java,v 1.1 2007-10-21 07:57:27 abyrne Exp $

  */

 public class Unique extends Index {

     /**

      * Returns <code>true</code>.

      * 

      * @return true

      */

     public final boolean isUnique() {

         return true;

     }

     /**

      * String representation of the index. This is an xml representation.

      * 

      * @return string representation in xml

      */

     public String toString() {

         StringBuffer result = new StringBuffer();

         result.append(" <unique name=\"").append(getName()).append("\">\n");

         List columns = getColumns();

         for (int i = 0; i < columns.size(); i++) {

             result.append("  <unique-column name=\"").append(columns.get(i)).append("\"/>\n");

         }

         result.append(" </unique>\n");

         return result.toString();

     }

 }