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


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.io.IOException JavaDoc;
42
43 import java.sql.SQLException JavaDoc;
44
45 import com.quadcap.sql.types.Value;
46 import com.quadcap.sql.types.ValueDefault;
47
48 import com.quadcap.util.Debug;
49
50 /**
51  * One part of a compiled <b>UPDATE</b> statement, including a column name and
52  * an expression which generates a value.
53  *
54  * @author Stan Bailes
55  */
56 public class UpdateItem {
57     String JavaDoc name;
58     Expression e;
59     Value v;
60     int col = -1;
61
62     public UpdateItem(String JavaDoc name, Expression e) {
63     this.name = name;
64     this.e = e;
65     }
66
67     void evaluate(Session session, Relation r, Cursor cursor)
68     throws SQLException JavaDoc, IOException JavaDoc
69     {
70     if (col < 0) {
71         Column c = cursor.getColumn(name);
72         if (c == null) {
73         throw new SQLException JavaDoc("Bad column: " + name, "42000");
74         }
75         col = c.getColumn();
76     }
77     v = e.getValue(session, cursor);
78     if (v instanceof ValueDefault) {
79         Column c = r.getColumn(col);
80         Expression ex = c.getDefault();
81         if (ex != null) {
82         v = ex.getValue(session, cursor);
83         }
84     }
85     }
86
87     public void update(Session session, Row row)
88     throws SQLException JavaDoc, IOException JavaDoc
89     {
90     row.set(col, v);
91     }
92 }
93
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