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Java > Open Source Codes > com > caucho > db > sql > DeleteQuery


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  *
23  * Free Software Foundation, Inc.
24  * 59 Temple Place, Suite 330
25  * Boston, MA 02111-1307 USA
26  *
27  * @author Scott Ferguson
28  */
29
30 package com.caucho.db.sql;
31
32 import com.caucho.db.Database;
33 import com.caucho.db.store.Transaction;
34 import com.caucho.db.table.Table;
35 import com.caucho.db.table.TableIterator;
36 import com.caucho.log.Log;
37 import com.caucho.util.CharBuffer;
38
39 import java.sql.SQLException JavaDoc;
40 import java.util.logging.Logger JavaDoc;
41
42 class DeleteQuery extends Query {
43   private static final Logger JavaDoc log = Log.open(DeleteQuery.class);
44
45   private final Table _table;
46
47   DeleteQuery(Database db, String JavaDoc sql, Table table)
48     throws SQLException JavaDoc
49   {
50     super(db, sql, null);
51     
52     _table = table;
53
54     setFromItems(new FromItem[] { new FromItem(table, table.getName()) });
55   }
56
57   public boolean isReadOnly()
58   {
59     return false;
60   }
61
62   /**
63    * Executes the query.
64    */
65   public void execute(QueryContext context, Transaction xa)
66     throws SQLException JavaDoc
67   {
68     int count = 0;
69     TableIterator []rows = new TableIterator[1];
70     rows[0] = _table.createTableIterator();
71     context.init(xa, rows, isReadOnly());
72
73     try {
74       if (! start(rows, rows.length, context, xa))
75     return;
76
77       do {
78     rows[0].delete();
79     
80     context.setRowUpdateCount(++count);
81       } while (nextTuple(rows, rows.length, context, xa));
82     } finally {
83       // autoCommitWrite must be before freeRows in case freeRows
84 // throws an exception
85 context.unlock();
86       
87       freeRows(rows, rows.length);
88     }
89   }
90
91   public String JavaDoc toString()
92   {
93     CharBuffer cb = new CharBuffer();
94     cb.append("DeleteQuery[");
95     if (_whereExpr != null) {
96       cb.append(",where:" + _whereExpr);
97     }
98     cb.append("]");
99     
100     return cb.close();
101   }
102 }
103
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