001    package org.apache.ojb.broker.query;
002    
003    /* Copyright 2002-2005 The Apache Software Foundation
004     *
005     * Licensed under the Apache License, Version 2.0 (the "License");
006     * you may not use this file except in compliance with the License.
007     * You may obtain a copy of the License at
008     *
009     *     http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    /**
019     * SelectionCriteria for [not] exists(sub query)
020     * 
021     * @author <a href="mailto:jbraeuchi@gmx.ch">Jakob Braeuchi</a>
022     * @version $Id: ExistsCriteria.java,v 1.1 2007-08-24 22:17:36 ewestfal Exp $
023     */
024    public class ExistsCriteria extends SelectionCriteria
025    {
026        private boolean m_negative = false;
027        /**
028         * Constructor for ExistsCriteria.
029         * @param subQuery
030         * @param negative  use negative form
031         */
032        ExistsCriteria(Query subQuery, boolean negative)
033        {
034            super("", subQuery, (String)null);
035            m_negative = negative;
036        }
037    
038        /*
039             * @see SelectionCriteria#getClause()
040             */
041        public String getClause()
042        {
043            if (m_negative)
044            {
045                return " NOT EXISTS";
046            }    
047            else
048            {
049                return " EXISTS";
050            }    
051        }
052    }