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


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.util.Vector JavaDoc;
47
48 import java.sql.SQLException JavaDoc;
49
50 import com.quadcap.sql.meta.MetaCursor;
51
52 import com.quadcap.util.Debug;
53
54 /**
55  * Table expression implementation of <b>TABLE</b> <i>table-name</i>.
56  *
57  * @author Stan Bailes
58  */
59 public class SelectFromTable extends TableExpression
60     implements Externalizable JavaDoc
61 {
62     String JavaDoc tableName;
63     Relation table = null;
64
65     /**
66      * Default constructor (required for Externalizable)
67      */
68     public SelectFromTable() {}
69
70     /**
71      * Constructor from specified table name
72      */
73     public SelectFromTable(String JavaDoc tableName) {
74     this.tableName = tableName;
75     }
76
77     /**
78      * We are a table expression;
79      */
80     public int rank() { return 2; }
81
82     /**
83      * And to prove it, here's our cursor.
84      */
85     public Cursor getCursor(Session session, Cursor cursor)
86     throws SQLException JavaDoc
87     {
88     if (table == null) {
89         try {
90         Database db = session.getDatabase();
91         table = db.getRelation(tableName);
92         } catch (IOException JavaDoc e) {
93         throw DbException.wrapThrowable(e);
94         }
95         if (table == null) {
96                 Cursor c = MetaCursor.find(session, tableName);
97                 if (c != null) return c;
98
99         throw new SQLException JavaDoc("No such table: " + tableName, "42000");
100         }
101     }
102     return table.getCursor(session, where, null, cursor);
103     }
104
105     /**
106      * Our cursor is even updateable; we are so cool
107      */
108     public boolean isUpdatable() {
109     return true;
110     }
111
112     /**
113      * TableExpression.getBaseTables(): We *are* the base table!
114      */
115     public void getBaseTables(Vector JavaDoc v) {
116     v.addElement(tableName);
117     }
118
119     /**
120      * Externalizable.readExternal(): Read me from a stream.
121      */
122     public void readExternal(ObjectInput JavaDoc in)
123     throws IOException JavaDoc, ClassNotFoundException JavaDoc
124     {
125     this.tableName = (String JavaDoc)in.readObject();
126     this.table = null;
127     }
128     
129     /**
130      * Externalizable.writeExternal(): Write me to a stream.
131      */
132     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
133     out.writeObject(tableName);
134     }
135
136     public String JavaDoc toString() {
137     return tableName;
138     }
139
140     /**
141      * Public accessor for table name
142      */
143     public String JavaDoc getTableName() {
144         return tableName;
145     }
146
147     /**
148      * Public 'setter' for table name
149      */
150     public void setTableName(String JavaDoc t) {
151         tableName = t;
152     }
153
154     //#ifdef DEBUG
155 public String JavaDoc name() { return tableName; }
156     //#endif
157 }
158
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