001/*
002 * Copyright 2006-2012 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.batch.item.database.support;
018
019import org.springframework.batch.item.database.PagingQueryProvider;
020import org.springframework.util.StringUtils;
021
022/**
023 * DB2 implementation of a {@link PagingQueryProvider} using
024 * database specific features.
025 *
026 * @author Thomas Risberg
027 * @author Michael Minella
028 * @since 2.0
029 */
030public class Db2PagingQueryProvider extends SqlWindowingPagingQueryProvider {
031
032        @Override
033        public String generateFirstPageQuery(int pageSize) {
034                return SqlPagingQueryUtils.generateLimitSqlQuery(this, false, buildLimitClause(pageSize));
035        }
036
037        @Override
038        public String generateRemainingPagesQuery(int pageSize) {
039                if(StringUtils.hasText(getGroupClause())) {
040                        return SqlPagingQueryUtils.generateLimitGroupedSqlQuery(this, true, buildLimitClause(pageSize));
041                }
042                else {
043                        return SqlPagingQueryUtils.generateLimitSqlQuery(this, true, buildLimitClause(pageSize));
044                }
045        }
046
047        @Override
048        protected Object getSubQueryAlias() {
049                return "AS TMP_SUB ";
050        }
051
052        private String buildLimitClause(int pageSize) {
053                return new StringBuilder().append("FETCH FIRST ").append(pageSize).append(" ROWS ONLY").toString();
054        }
055
056}