01: /*
02: * $Id: DMLWhenClause.java,v 1.7 2005/12/20 18:32:28 ahimanikya Exp $
03: * =======================================================================
04: * Copyright (c) 2004-2005 Axion Development Team. All rights reserved.
05: *
06: * Redistribution and use in source and binary forms, with or without
07: * modification, are permitted provided that the following conditions
08: * are met:
09: *
10: * 1. Redistributions of source code must retain the above
11: * copyright notice, this list of conditions and the following
12: * disclaimer.
13: *
14: * 2. Redistributions in binary form must reproduce the above copyright
15: * notice, this list of conditions and the following disclaimer in
16: * the documentation and/or other materials provided with the
17: * distribution.
18: *
19: * 3. The names "Tigris", "Axion", nor the names of its contributors may
20: * not be used to endorse or promote products derived from this
21: * software without specific prior written permission.
22: *
23: * 4. Products derived from this software may not be called "Axion", nor
24: * may "Tigris" or "Axion" appear in their names without specific prior
25: * written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
30: * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
31: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
32: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
33: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
37: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38: * =======================================================================
39: */
40:
41: package org.axiondb.engine.commands;
42:
43: import org.axiondb.AxionException;
44: import org.axiondb.Database;
45: import org.axiondb.RowDecorator;
46: import org.axiondb.Selectable;
47: import org.axiondb.TableIdentifier;
48: import org.axiondb.engine.visitors.ResolveSelectableVisitor;
49:
50: /**
51: * A <tt>WHEN</tt> clause in insert, update and merge statements.
52: *
53: * @author Ritesh Adval
54: * @author Jonathan Giron
55: */
56: public class DMLWhenClause {
57:
58: public DMLWhenClause(Selectable whenCondition) {
59: _condition = whenCondition;
60: }
61:
62: public boolean evaluate(RowDecorator dec) throws AxionException {
63: if (_condition == null) {
64: throw new AxionException("Condition can't be evaluated: "
65: + _condition);
66: }
67:
68: // SQL 2003 standard does not specify a when clause, but we opt to apply the
69: // applicable general rule for the where condition, ISO/IEC 9075-2:2003,
70: // Section 7.8, General Rule 2 - filter is applied if condition evaluates to true; null
71: // evaluation thus maps to false.
72: Boolean result = (Boolean) _condition.evaluate(dec);
73: return (result == null) ? false : result.booleanValue();
74: }
75:
76: public void resolve(Database db, TableIdentifier[] tables)
77: throws AxionException {
78: ResolveSelectableVisitor resolveSel = new ResolveSelectableVisitor(
79: db);
80: _condition = resolveSel.visit(_condition, null, tables);
81: }
82:
83: public Selectable getCondition() {
84: return _condition;
85: }
86:
87: private Selectable _condition;
88: }
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