KickJava   Java API By Example, From Geeks To Geeks.

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


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.io.Extern;
49
50 import com.quadcap.util.Debug;
51
52 /**
53  * Log Step to alter the definition of a table column.
54  *
55  * @author Stan Bailes
56  */
57 public class AlterColumn extends LogStep implements Externalizable JavaDoc {
58     transient Table table;
59     transient Column column;
60
61     String JavaDoc columnName = null;
62     String JavaDoc tableName = null;
63     Expression oldDefault = null;
64     Expression newDefault = null;
65
66     /**
67      * Default constructor
68      */
69     public AlterColumn() {}
70
71     /**
72      * Explicit constructor from table, column name and new default value
73      */
74     public AlterColumn(Session session, Table table,
75                        String JavaDoc columnName, Expression newDefault) {
76         super(session);
77     this.table = table;
78     this.tableName = table.getName();
79     this.columnName = columnName;
80     this.newDefault = newDefault;
81     }
82
83     Table getTable(Database db) throws IOException JavaDoc {
84     if (table == null) {
85         table = (Table)db.getRelation(tableName);
86     }
87     return table;
88     }
89     
90     public void undo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
91     Database db = session.getDatabase();
92     getTable(db);
93     column = table.getColumn(columnName);
94     column.setDefault(oldDefault);
95     db.updateRelation(table);
96     }
97
98     public void redo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
99     Database db = session.getDatabase();
100     getTable(db);
101     column.setDefault(newDefault);
102     db.updateRelation(table);
103     }
104
105     public void prepare(Session session) throws IOException JavaDoc, SQLException JavaDoc {
106     column = table.getColumn(columnName);
107     if (oldDefault == null) {
108         oldDefault = column.getDefault();
109     }
110     }
111     
112     public void readExternal(ObjectInput JavaDoc in)
113     throws IOException JavaDoc, ClassNotFoundException JavaDoc
114     {
115     super.readExternal(in);
116     this.columnName = (String JavaDoc)in.readObject();
117     this.tableName = (String JavaDoc)in.readObject();
118     this.oldDefault = (Expression)in.readObject();
119     this.newDefault = (Expression)in.readObject();
120     }
121     
122     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
123     super.writeExternal(out);
124     out.writeObject(columnName);
125     out.writeObject(tableName);
126     out.writeObject(oldDefault);
127     out.writeObject(newDefault);
128     }
129
130     //#ifdef DEBUG
131 public String JavaDoc toString() {
132     StringBuffer JavaDoc sb = new StringBuffer JavaDoc(super.toString());
133         sb.append(" AlterColumn(");
134     sb.append(tableName);
135     sb.append(',');
136     sb.append(columnName);
137     sb.append(" set default " + newDefault);
138     sb.append(")");
139     return sb.toString();
140     }
141     //#endif
142
143     static Extern extern = null;
144     public Extern getExtern() { return extern; }
145     public void setExtern(Extern extern) { AlterColumn.extern = extern; }
146 }
147
Popular Tags