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Java > Open Source Codes > com > quadcap > sql > HavingCursor


1 package com.quadcap.sql;
2
3 /* Copyright 1999 - 2003 Quadcap Software. All rights reserved.
4  *
5  * This software is distributed under the Quadcap Free Software License.
6  * This software may be used or modified for any purpose, personal or
7  * commercial. Open Source redistributions are permitted. Commercial
8  * redistribution of larger works derived from, or works which bundle
9  * this software requires a "Commercial Redistribution License"; see
10  * http://www.quadcap.com/purchase.
11  *
12  * Redistributions qualify as "Open Source" under one of the following terms:
13  *
14  * Redistributions are made at no charge beyond the reasonable cost of
15  * materials and delivery.
16  *
17  * Redistributions are accompanied by a copy of the Source Code or by an
18  * irrevocable offer to provide a copy of the Source Code for up to three
19  * years at the cost of materials and delivery. Such redistributions
20  * must allow further use, modification, and redistribution of the Source
21  * Code under substantially the same terms as this license.
22  *
23  * Redistributions of source code must retain the copyright notices as they
24  * appear in each source code file, these license terms, and the
25  * disclaimer/limitation of liability set forth as paragraph 6 below.
26  *
27  * Redistributions in binary form must reproduce this Copyright Notice,
28  * these license terms, and the disclaimer/limitation of liability set
29  * forth as paragraph 6 below, in the documentation and/or other materials
30  * provided with the distribution.
31  *
32  * The Software is provided on an "AS IS" basis. No warranty is
33  * provided that the Software is free of defects, or fit for a
34  * particular purpose.
35  *
36  * Limitation of Liability. Quadcap Software shall not be liable
37  * for any damages suffered by the Licensee or any third party resulting
38  * from use of the Software.
39  */
40
41 import java.util.Vector JavaDoc;
42
43 import java.sql.SQLException JavaDoc;
44
45 import com.quadcap.sql.types.Value;
46 import com.quadcap.sql.types.ValueBoolean;
47
48 import com.quadcap.util.Debug;
49
50 /**
51  * Cursor to support <b>HAVING</b> clause.
52  *
53  * <p>XXX Optimize this by use of a 'HavingRow' class which would perform less
54  * copying.</p>
55  *
56  * @author Stan Bailes
57  */
58 public class HavingCursor extends FilterCursor {
59     Row row = null;
60
61     public HavingCursor(Session session, Cursor cursor) throws SQLException JavaDoc {
62     super(session, cursor);
63     }
64
65     public Row getRow() throws SQLException JavaDoc {
66     return row;
67     }
68
69     public void updateRow(Row row) throws SQLException JavaDoc {
70     this.row = row;
71     Row t = new Row(row.size()-1);
72     for (int i = 1; i <= row.size(); i++) {
73         t.set(i, row.item(i));
74     }
75     cursor.updateRow(t);
76     }
77
78     public int getColumnCount() throws SQLException JavaDoc {
79     return cursor.getColumnCount() - 1;
80     }
81
82     public boolean next() throws SQLException JavaDoc {
83     final int size = cursor.getColumnCount();
84     boolean have = false;
85     while (!have && cursor.next()) {
86         Row r = cursor.getRow();
87         Value val = r.item(size);
88         if (val instanceof ValueBoolean &&
89         ((ValueBoolean)val).isTrue()) {
90         if (this.row == null) {
91             this.row = new Row(size-1);
92         }
93         for (int i = 1; i < size; i++) row.set(i, r.item(i));
94         have = true;
95         }
96     }
97     return have;
98     }
99
100 }
101
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