| 1 | /* |
| 2 | * Copyright 2006-2012 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.springframework.batch.item.database.support; |
| 18 | |
| 19 | import java.util.LinkedHashMap; |
| 20 | import java.util.Map; |
| 21 | |
| 22 | import org.springframework.batch.item.database.Order; |
| 23 | import org.springframework.util.StringUtils; |
| 24 | |
| 25 | /** |
| 26 | * Generic Paging Query Provider using standard SQL:2003 windowing functions. |
| 27 | * These features are supported by DB2, Oracle, SQL Server 2005, Sybase and |
| 28 | * Apache Derby version 10.4.1.3 |
| 29 | * |
| 30 | * @author Thomas Risberg |
| 31 | * @author Michael Minella |
| 32 | * @since 2.0 |
| 33 | */ |
| 34 | public class SqlWindowingPagingQueryProvider extends AbstractSqlPagingQueryProvider { |
| 35 | |
| 36 | @Override |
| 37 | public String generateFirstPageQuery(int pageSize) { |
| 38 | StringBuilder sql = new StringBuilder(); |
| 39 | sql.append("SELECT * FROM ( "); |
| 40 | sql.append("SELECT ").append(StringUtils.hasText(getOrderedQueryAlias()) ? getOrderedQueryAlias() + ".*, " : "*, "); |
| 41 | sql.append("ROW_NUMBER() OVER (").append(getOverClause()); |
| 42 | sql.append(") AS ROW_NUMBER"); |
| 43 | sql.append(getOverSubstituteClauseStart()); |
| 44 | sql.append(" FROM ").append(getFromClause()).append( |
| 45 | getWhereClause() == null ? "" : " WHERE " + getWhereClause()); |
| 46 | sql.append(getGroupClause() == null ? "" : " GROUP BY " + getGroupClause()); |
| 47 | sql.append(getOverSubstituteClauseEnd()); |
| 48 | sql.append(") ").append(getSubQueryAlias()).append("WHERE ").append(extractTableAlias()).append( |
| 49 | "ROW_NUMBER <= ").append(pageSize); |
| 50 | sql.append(" ORDER BY ").append(SqlPagingQueryUtils.buildSortClause(this)); |
| 51 | |
| 52 | return sql.toString(); |
| 53 | } |
| 54 | |
| 55 | protected String getOrderedQueryAlias() { |
| 56 | return ""; |
| 57 | } |
| 58 | |
| 59 | protected Object getSubQueryAlias() { |
| 60 | return "AS TMP_SUB "; |
| 61 | } |
| 62 | |
| 63 | protected Object extractTableAlias() { |
| 64 | String alias = "" + getSubQueryAlias(); |
| 65 | if (StringUtils.hasText(alias) && alias.toUpperCase().startsWith("AS")) { |
| 66 | alias = alias.substring(3).trim() + "."; |
| 67 | } |
| 68 | return alias; |
| 69 | } |
| 70 | |
| 71 | @Override |
| 72 | public String generateRemainingPagesQuery(int pageSize) { |
| 73 | StringBuilder sql = new StringBuilder(); |
| 74 | sql.append("SELECT * FROM ( "); |
| 75 | sql.append("SELECT ").append(StringUtils.hasText(getOrderedQueryAlias()) ? getOrderedQueryAlias() + ".*, " : "*, "); |
| 76 | sql.append("ROW_NUMBER() OVER (").append(getOverClause()); |
| 77 | sql.append(") AS ROW_NUMBER"); |
| 78 | sql.append(getOverSubstituteClauseStart()); |
| 79 | sql.append(" FROM ").append(getFromClause()); |
| 80 | if (getWhereClause() != null) { |
| 81 | sql.append(" WHERE "); |
| 82 | sql.append(getWhereClause()); |
| 83 | } |
| 84 | |
| 85 | sql.append(getGroupClause() == null ? "" : " GROUP BY " + getGroupClause()); |
| 86 | sql.append(getOverSubstituteClauseEnd()); |
| 87 | sql.append(") ").append(getSubQueryAlias()).append("WHERE ").append(extractTableAlias()).append( |
| 88 | "ROW_NUMBER <= ").append(pageSize); |
| 89 | sql.append(" AND "); |
| 90 | SqlPagingQueryUtils.buildSortConditions(this, sql); |
| 91 | sql.append(" ORDER BY ").append(SqlPagingQueryUtils.buildSortClause(this)); |
| 92 | |
| 93 | return sql.toString(); |
| 94 | } |
| 95 | |
| 96 | @Override |
| 97 | public String generateJumpToItemQuery(int itemIndex, int pageSize) { |
| 98 | int page = itemIndex / pageSize; |
| 99 | int lastRowNum = (page * pageSize); |
| 100 | if (lastRowNum <= 0) { |
| 101 | lastRowNum = 1; |
| 102 | } |
| 103 | |
| 104 | StringBuilder sql = new StringBuilder(); |
| 105 | sql.append("SELECT "); |
| 106 | buildSortKeySelect(sql, getSortKeysReplaced(extractTableAlias())); |
| 107 | sql.append(" FROM ( "); |
| 108 | sql.append("SELECT "); |
| 109 | buildSortKeySelect(sql); |
| 110 | sql.append(", ROW_NUMBER() OVER (").append(getOverClause()); |
| 111 | sql.append(") AS ROW_NUMBER"); |
| 112 | sql.append(getOverSubstituteClauseStart()); |
| 113 | sql.append(" FROM ").append(getFromClause()); |
| 114 | sql.append(getWhereClause() == null ? "" : " WHERE " + getWhereClause()); |
| 115 | sql.append(getGroupClause() == null ? "" : " GROUP BY " + getGroupClause()); |
| 116 | sql.append(getOverSubstituteClauseEnd()); |
| 117 | sql.append(") ").append(getSubQueryAlias()).append("WHERE ").append(extractTableAlias()).append( |
| 118 | "ROW_NUMBER = ").append(lastRowNum); |
| 119 | sql.append(" ORDER BY ").append(SqlPagingQueryUtils.buildSortClause(getSortKeysReplaced(extractTableAlias()))); |
| 120 | |
| 121 | return sql.toString(); |
| 122 | } |
| 123 | |
| 124 | private Map<String, Order> getSortKeysReplaced(Object qualifierReplacement) { |
| 125 | final String newQualifier = "" + qualifierReplacement; |
| 126 | final Map<String, Order> sortKeys = new LinkedHashMap<String, Order>(); |
| 127 | for (Map.Entry<String, Order> sortKey : getSortKeys().entrySet()) { |
| 128 | sortKeys.put(sortKey.getKey().replaceFirst("^.*\\.", newQualifier), sortKey.getValue()); |
| 129 | } |
| 130 | return sortKeys; |
| 131 | } |
| 132 | |
| 133 | private void buildSortKeySelect(StringBuilder sql) { |
| 134 | buildSortKeySelect(sql, null); |
| 135 | } |
| 136 | |
| 137 | private void buildSortKeySelect(StringBuilder sql, Map<String, Order> sortKeys) { |
| 138 | String prefix = ""; |
| 139 | if (sortKeys == null) { |
| 140 | sortKeys = getSortKeys(); |
| 141 | } |
| 142 | for (Map.Entry<String, Order> sortKey : sortKeys.entrySet()) { |
| 143 | sql.append(prefix); |
| 144 | prefix = ", "; |
| 145 | sql.append(sortKey.getKey()); |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | protected String getOverClause() { |
| 150 | StringBuilder sql = new StringBuilder(); |
| 151 | |
| 152 | sql.append(" ORDER BY ").append(SqlPagingQueryUtils.buildSortClause(this)); |
| 153 | |
| 154 | return sql.toString(); |
| 155 | } |
| 156 | |
| 157 | protected String getOverSubstituteClauseStart() { |
| 158 | return ""; |
| 159 | } |
| 160 | |
| 161 | protected String getOverSubstituteClauseEnd() { |
| 162 | return ""; |
| 163 | } |
| 164 | } |