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


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.IOException JavaDoc;
44
45 import java.sql.ResultSet JavaDoc;
46 import java.sql.SQLException JavaDoc;
47
48 import com.quadcap.sql.index.Btree;
49
50 import com.quadcap.util.Debug;
51
52 /**
53  * Implementation of the SQL <B>DELETE</B> statement.
54  *
55  * @author Stan Bailes
56  */
57
58
59 public class StmtDelete implements Stmt {
60     String JavaDoc tableName;
61     SelectExpression select;
62
63     /**
64      * Default constructor
65      */
66     public StmtDelete() {}
67
68     /**
69      * Explicit constructor from table name and predicate
70      */
71     public StmtDelete(String JavaDoc tableName, Expression predicate) {
72     this.tableName = tableName;
73     this.select = new SelectExpression(tableName, predicate);
74     }
75
76     /**
77      * Execute the delete operation: Get a table cursor, maybe one with
78      * a predicate (if there's a "WHERE", implying that we really don't
79      * want to delete *all* the rows.)
80      */
81     public void execute(Session session) throws IOException JavaDoc, SQLException JavaDoc {
82     try {
83             Database db = session.getDatabase();
84             Relation t = db.getRelation(tableName);
85             if (t == null) {
86                 throw new SQLException JavaDoc("No such table/view: " + tableName,
87                                        "42000");
88             }
89             if (!t.isUpdatable()) {
90                 throw new SQLException JavaDoc("Not updatable: " + tableName,
91                                        "42000");
92             }
93         session.getTableWriteLock(tableName);
94             Cursor delCursor = select.getCursor(session, null);
95             try {
96                 while (delCursor.next()) {
97                     delCursor.deleteRow();
98                 }
99             } finally {
100                 delCursor.close();
101             }
102     } catch (IOException JavaDoc e) {
103         throw DbException.wrapThrowable(e);
104     }
105           
106     }
107 }
108     
109
110
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