View Javadoc

1   package org.apache.torque.engine.database.model;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import java.util.List;
23  
24  /***
25   * Information about unique columns of a table.  This class assumes
26   * that in the underlying RDBMS, unique constraints and unique indices
27   * are roughly equivalent.  For example, adding a unique constraint to
28   * a column also creates an index on that column (this is known to be
29   * true for MySQL and Oracle).
30   *
31   * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
32   * @author <a href="mailto:dlr@collab.net">Daniel Rall</a>
33   * @version $Id: Unique.java 473814 2006-11-11 22:30:30Z tv $
34   */
35  public class Unique extends Index
36  {
37      /***
38       * Returns <code>true</code>.
39       *
40       * @return true
41       */
42      public final boolean isUnique()
43      {
44          return true;
45      }
46  
47      /***
48       * String representation of the index. This is an xml representation.
49       *
50       * @return string representation in xml
51       */
52      public String toString()
53      {
54          StringBuffer result = new StringBuffer();
55          result.append(" <unique name=\"")
56              .append(getName())
57              .append("\">\n");
58  
59          List columns = getColumns();
60          for (int i = 0; i < columns.size(); i++)
61          {
62              result.append("  <unique-column name=\"")
63                  .append(columns.get(i))
64                  .append("\"/>\n");
65          }
66          result.append(" </unique>\n");
67          return result.toString();
68      }
69  }