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


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.util.Vector JavaDoc;
42
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.ResultSet JavaDoc;
49 import java.sql.SQLException JavaDoc;
50
51 import com.quadcap.sql.io.Extern;
52 import com.quadcap.util.Debug;
53
54 /**
55  * Implementation of the SQL <b>CREATE VIEW</b> statement.
56  *
57  * @author Stan Bailes
58  */
59
60 public class StmtCreateView extends LogStep implements Stmt, Externalizable JavaDoc {
61     View view;
62
63     /**
64      * Default constructor
65      */
66     public StmtCreateView() {}
67
68     /**
69      * Explicit constructor from View (parser)
70      */
71     public StmtCreateView(Session session, View view) {
72         super(session);
73     this.view = view;
74     }
75
76     /**
77      * LogStep.undo(): Remove the view
78      */
79     public void undo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
80     Database db = session.getDatabase();
81     db.removeRelation(view.getName());
82     }
83
84     /**
85      * LogStep.redo(): Add the view and record the view dependency relations
86      */
87     public void redo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
88     Database db = session.getDatabase();
89     Vector JavaDoc v = view.getBaseTables();
90     
91     for (int i = 0; i < v.size(); i++) {
92         String JavaDoc base = (String JavaDoc)v.elementAt(i);
93         db.checkViewDependency(base, view.getName());
94     }
95
96     view.addColumns(session);
97     db.addRelation(view);
98     for (int i = 0; i < v.size(); i++) {
99         String JavaDoc base = (String JavaDoc)v.elementAt(i);
100         db.addViewDependency(base, view.getName());
101     }
102     }
103     
104     public void execute(Session session) throws IOException JavaDoc, SQLException JavaDoc {
105     session.getTableWriteLock("#Schema");
106     view.addColumns(session);
107     session.doStep(this);
108     }
109
110     public void prepare(Session session) throws IOException JavaDoc, SQLException JavaDoc {
111     }
112
113     public void readExternal(ObjectInput JavaDoc in)
114     throws IOException JavaDoc, ClassNotFoundException JavaDoc
115     {
116     super.readExternal(in);
117     view = (View)in.readObject();
118     }
119     
120     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
121     super.writeExternal(out);
122     out.writeObject(view);
123     }
124
125     //#ifdef DEBUG
126 /**
127      * Return a displayable representation for debugging
128      */
129     public String JavaDoc toString() {
130     StringBuffer JavaDoc sb = new StringBuffer JavaDoc(super.toString());
131     sb.append(" CreateView(");
132     sb.append(view.toString());
133     sb.append(')');
134     return sb.toString();
135     }
136     //#endif
137
138     static Extern extern;
139     public void setExtern(Extern extern) { StmtCreateView.extern = extern; }
140     public Extern getExtern() { return extern; }
141 }
142
143
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