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();

     }

 }