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


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.BufferedInputStream JavaDoc;
42 import java.io.BufferedOutputStream JavaDoc;
43 import java.io.Externalizable JavaDoc;
44 import java.io.IOException JavaDoc;
45 import java.io.ObjectInput JavaDoc;
46 import java.io.ObjectOutput JavaDoc;
47
48 import java.sql.SQLException JavaDoc;
49
50 import com.quadcap.sql.file.ByteUtil;
51 import com.quadcap.sql.file.PageManager;
52 import com.quadcap.sql.file.RandomAccess;
53 import com.quadcap.sql.file.RandomAccessInputStream;
54 import com.quadcap.sql.file.RandomAccessOutputStream;
55
56 import com.quadcap.sql.io.ObjectInputStream;
57 import com.quadcap.sql.io.ObjectOutputStream;
58 import com.quadcap.sql.io.Extern;
59
60 import com.quadcap.sql.index.Btree;
61
62 import com.quadcap.sql.types.Value;
63 import com.quadcap.sql.types.ValueNull;
64
65 import com.quadcap.io.CountedInputStream;
66
67 import com.quadcap.util.Debug;
68
69 /**
70  * Log step to add a column to a table, supplying default values as necessary.
71  *
72  * @author Stan Bailes
73  */
74 public class AddColumn extends LogStep implements Externalizable JavaDoc {
75     transient Table table;
76
77     Column column;
78     String JavaDoc tableName = null;
79     int pos = -1;
80
81     /**
82      * Default constructor
83      */
84     public AddColumn() {}
85
86     /**
87      * Explicit constructor from table and column
88      */
89     public AddColumn(Session session, Table table, Column column, int pos) {
90         super(session);
91     this.table = table;
92     this.tableName = table.getName();
93     this.column = column;
94         this.pos = pos;
95     }
96
97     /**
98      * Lazy table accessor
99      */
100     Table getTable(Database db) throws IOException JavaDoc {
101     if (table == null) {
102         table = (Table)db.getRelation(tableName);
103     }
104     return table;
105     }
106
107     /**
108      * LogStep.undo(), our job is to remove the column definition from the
109      * schema.
110      */
111     public void undo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
112     Database db = session.getDatabase();
113     getTable(db);
114     Column c = table.getColumn(column.getName());
115     table.deleteColumn(c.getColumn());
116     db.updateRelation(table);
117     }
118
119     /**
120      * LogStep.redo(), our job is to add the column and update the table
121      * definition to include the new column.
122      */
123     public void redo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
124     Database db = session.getDatabase();
125     getTable(db);
126         if (pos > 0) {
127             table.addColumn(column, pos);
128         } else {
129             table.addColumn(column);
130         }
131     db.updateRelation(table);
132     }
133
134     /**
135      * Read me from a stream
136      */
137     public void readExternal(ObjectInput JavaDoc in)
138     throws IOException JavaDoc, ClassNotFoundException JavaDoc
139     {
140     super.readExternal(in);
141     this.column = (Column)in.readObject();
142     this.tableName = (String JavaDoc)in.readObject();
143         this.pos = in.readInt();
144     }
145
146     /**
147      * Write me to a stream
148      */
149     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
150     super.writeExternal(out);
151     out.writeObject(column);
152     out.writeObject(tableName);
153         out.writeInt(pos);
154     }
155
156     //#ifdef DEBUG
157 /**
158      * Return a string representation for display/debugging purposes
159      */
160     public String JavaDoc toString() {
161     StringBuffer JavaDoc sb = new StringBuffer JavaDoc(super.toString());
162         sb.append(" AddColumn(");
163     sb.append(tableName);
164     sb.append(',');
165     sb.append(column.toString());
166         if (pos > 0) {
167             sb.append(',');
168             sb.append(pos);
169         }
170         sb.append(")");
171     return sb.toString();
172     }
173     //#endif
174
175     /**
176      * My class's Extern object (see com.quadcap.sql.io.Extern)
177      */
178     static Extern extern;
179     public void setExtern(Extern extern) { AddColumn.extern = extern; }
180     public Extern getExtern() { return extern; }
181 }
182
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