01: /*
02: * $Id: CountFunction.java,v 1.9 2005/04/24 21:33:11 ahimanikya Exp $
03: * =======================================================================
04: * Copyright (c) 2002-2005 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.functions;
42:
43: import org.axiondb.AxionException;
44: import org.axiondb.DataType;
45: import org.axiondb.FunctionFactory;
46: import org.axiondb.RowDecoratorIterator;
47: import org.axiondb.Selectable;
48: import org.axiondb.types.IntegerType;
49:
50: /**
51: * <code>COUNT</code>: an aggregate function returning the number of rows.
52: *
53: * @version $Revision: 1.9 $ $Date: 2005/04/24 21:33:11 $
54: * @author Rodney Waldhoff
55: * @author Chuck Burdick
56: * @author Ahimanikya Satapathy
57: */
58: public class CountFunction extends BaseAggregateFunction implements
59: AggregateFunction, FunctionFactory {
60: public CountFunction() {
61: super ("COUNT");
62: }
63:
64: public ConcreteFunction makeNewInstance() {
65: return new CountFunction();
66: }
67:
68: public DataType getDataType() {
69: return RETURN_TYPE;
70: }
71:
72: public Object evaluate(RowDecoratorIterator rows)
73: throws AxionException {
74: int count = 0;
75: setDistinct();
76: Selectable sel = getArgument(0);
77:
78: if (isDistinct()) {
79: if (sel.getName().equals("*")) {
80: throw new AxionException(
81: "Invalid Expression, Use COUNT(DISTINCT <column>)");
82: }
83:
84: while (rows.hasNext()) {
85: Object rawVal = sel.evaluate(rows.next());
86: DataType type = sel.getDataType();
87: Object val = type.convert(rawVal);
88: if (acceptable(val)) {
89: count++;
90: }
91: }
92: } else {
93: count = rows.size();
94: }
95: return new Integer(count);
96: }
97:
98: private static final DataType RETURN_TYPE = new IntegerType();
99: }
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