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


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.Externalizable JavaDoc;
42 import java.io.IOException JavaDoc;
43 import java.io.ObjectInput JavaDoc;
44 import java.io.ObjectOutput JavaDoc;
45
46 import java.sql.SQLException JavaDoc;
47
48 import com.quadcap.sql.types.Value;
49 import com.quadcap.sql.types.ValueBoolean;
50 import com.quadcap.sql.types.ValueUnknown;
51
52 /**
53  * Constraint class for SQL <b>CHECK</b> constraints.
54  *
55  * @author Stan Bailes
56  */
57 public class CheckConstraint extends Constraint implements Externalizable JavaDoc {
58     Expression expression;
59     
60     public CheckConstraint() {}
61
62     public CheckConstraint(String JavaDoc name, Expression expression) {
63     super(name);
64     this.expression = expression;
65     }
66
67     public void add(Session session) throws SQLException JavaDoc {
68     if (!table.isUnderConstruction()) {
69         Cursor c = table.getCursor(session, null, null);
70         if (c != null) {
71                 try {
72                     while (c.next()) {
73                         checkValue(expression.getValue(session, c));
74                     }
75                 } finally {
76                     c.close();
77                 }
78         }
79     }
80     }
81     
82     public void delete(Session session) {}
83     public void undoDelete(Session session) {}
84
85     public void applyInsert(Session session, Row row, long rowId,
86                 Constraint activeIndex)
87     throws SQLException JavaDoc, IOException JavaDoc
88     {
89     }
90     
91     public void applyDelete(Session session, Row row, long rowId,
92                 Constraint activeIndex)
93     throws SQLException JavaDoc, IOException JavaDoc
94     {
95     }
96
97     public final void checkValue(Value val) throws SQLException JavaDoc {
98     if (!(val instanceof ValueBoolean)) {
99         if (val instanceof ValueUnknown) return;
100         throw new SQLException JavaDoc("Bad check expression: " + expression +
101                    ", value = " + val, "42000");
102     }
103     if (!((ValueBoolean)val).isTrue()) {
104         throw new SQLException JavaDoc("Check constraint violated: " +
105                    expression, "23000");
106     }
107     }
108     
109     public void checkInsert(Session session, Row row)
110     throws SQLException JavaDoc, IOException JavaDoc
111     {
112     StaticCursor cursor = new StaticCursor(session, table, row);
113     cursor.next();
114     checkValue(expression.getValue(session, cursor));
115     }
116
117     public void checkUpdate(Session session, byte[] oldKey, Row row,
118                             Row oldRow, long rowId, Constraint activeIndex)
119     throws SQLException JavaDoc, IOException JavaDoc
120     {
121     checkInsert(session, row);
122     }
123     
124     public void checkDelete(Session session, Row row, long rowId)
125     throws SQLException JavaDoc, IOException JavaDoc
126     {
127     }
128     
129     public void applyUpdate(Session session, byte[] oldKey, Row row,
130                 Row oldRow, long rowId, Constraint activeIndex)
131     throws SQLException JavaDoc, IOException JavaDoc
132     {
133     }
134
135     public void readExternal(ObjectInput JavaDoc in)
136     throws IOException JavaDoc, ClassNotFoundException JavaDoc
137     {
138     super.readExternal(in);
139     expression = (Expression)in.readObject();
140     }
141     
142     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
143     super.writeExternal(out);
144     out.writeObject(expression);
145     }
146 }
147
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