001: /*
002: * $Id: DatePartFunction.java,v 1.7 2005/05/02 22:28:41 ahimanikya Exp $
003: * =======================================================================
004: * Copyright (c) 2002-2005 Axion Development Team. All rights reserved.
005: *
006: * Redistribution and use in source and binary forms, with or without
007: * modification, are permitted provided that the following conditions
008: * are met:
009: *
010: * 1. Redistributions of source code must retain the above
011: * copyright notice, this list of conditions and the following
012: * disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The names "Tigris", "Axion", nor the names of its contributors may
020: * not be used to endorse or promote products derived from this
021: * software without specific prior written permission.
022: *
023: * 4. Products derived from this software may not be called "Axion", nor
024: * may "Tigris" or "Axion" appear in their names without specific prior
025: * written permission.
026: *
027: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
028: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
029: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
030: * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
031: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
032: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
033: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
034: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
035: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
036: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
037: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
038: * =======================================================================
039: */
040:
041: package org.axiondb.functions;
042:
043: import java.sql.Timestamp;
044:
045: import org.axiondb.AxionException;
046: import org.axiondb.DataType;
047: import org.axiondb.FunctionFactory;
048: import org.axiondb.RowDecorator;
049: import org.axiondb.Selectable;
050: import org.axiondb.types.StringType;
051: import org.axiondb.types.TimestampType;
052: import org.axiondb.util.DateTimeUtils;
053:
054: /**
055: * Syntax: DatePart(date-part, date-src) or EXTRACT(date-part FROM date-src)
056: *
057: * @version $Revision: 1.7 $ $Date: 2005/05/02 22:28:41 $
058: * @author Jonathan Giron
059: */
060: public class DatePartFunction extends BaseFunction implements
061: ScalarFunction, FunctionFactory {
062:
063: /** Creates a new instance of Class */
064: public DatePartFunction() {
065: super ("DATEPART");
066: }
067:
068: public ConcreteFunction makeNewInstance() {
069: return new DatePartFunction();
070: }
071:
072: /** {@link DataType} */
073: public DataType getDataType() {
074: return RETURN_TYPE;
075: }
076:
077: /**
078: * Returns String representation of requested portion of given timestamp. <br>
079: * Valid parts are {'day', 'month', 'year', 'second', 'millisecond', 'minute', 'hour',
080: * 'week', 'quarter'}
081: */
082: public Object evaluate(RowDecorator row) throws AxionException {
083: Timestamp timestamp = null;
084:
085: // Get 'part-identifier'
086: Selectable sel = getArgument(0);
087: String partType = (String) RETURN_TYPE.convert(sel
088: .evaluate(row));
089: String partIdent = DateTimeUtils.getPartMnemonicFor(partType);
090:
091: // Get Date source
092: Object dateSrc = getArgument(1).evaluate(row);
093:
094: if (dateSrc == null) {
095: return null;
096: } else {
097: timestamp = (Timestamp) TIMESTAMP_TYPE.convert(dateSrc);
098: }
099:
100: return DateTimeUtils.getDatePart(timestamp, partIdent);
101: }
102:
103: public boolean isValid() {
104: return (getArgumentCount() == 2);
105: }
106:
107: private static final DataType TIMESTAMP_TYPE = new TimestampType();
108: private static final DataType RETURN_TYPE = new StringType();
109: }
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