| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.nifi.processors.standard.db.impl; |
| |
| import org.apache.commons.lang3.StringUtils; |
| import org.apache.nifi.processors.standard.db.DatabaseAdapter; |
| |
| /** |
| * A DatabaseAdapter that generates Oracle-compliant SQL. |
| */ |
| public class OracleDatabaseAdapter implements DatabaseAdapter { |
| @Override |
| public String getName() { |
| return "Oracle"; |
| } |
| |
| @Override |
| public String getDescription() { |
| return "Generates Oracle compliant SQL"; |
| } |
| |
| @Override |
| public String getSelectStatement(String tableName, String columnNames, String whereClause, String orderByClause, Long limit, Long offset) { |
| return getSelectStatement(tableName, columnNames, whereClause, orderByClause, limit, offset, null); |
| } |
| |
| @Override |
| public String getSelectStatement(String tableName, String columnNames, String whereClause, String orderByClause, Long limit, Long offset, String columnForPartitioning) { |
| if (StringUtils.isEmpty(tableName)) { |
| throw new IllegalArgumentException("Table name cannot be null or empty"); |
| } |
| |
| final StringBuilder query = new StringBuilder(); |
| boolean nestedSelect = (limit != null || offset != null) && StringUtils.isEmpty(columnForPartitioning); |
| if (nestedSelect) { |
| // Need a nested SELECT query here in order to use ROWNUM to limit the results |
| query.append("SELECT "); |
| if (StringUtils.isEmpty(columnNames) || columnNames.trim().equals("*")) { |
| query.append("*"); |
| } else { |
| query.append(columnNames); |
| } |
| query.append(" FROM (SELECT a.*, ROWNUM rnum FROM ("); |
| } |
| |
| query.append("SELECT "); |
| if (StringUtils.isEmpty(columnNames) || columnNames.trim().equals("*")) { |
| query.append("*"); |
| } else { |
| query.append(columnNames); |
| } |
| query.append(" FROM "); |
| query.append(tableName); |
| |
| if (!StringUtils.isEmpty(whereClause)) { |
| query.append(" WHERE "); |
| query.append(whereClause); |
| if (!StringUtils.isEmpty(columnForPartitioning)) { |
| query.append(" AND "); |
| query.append(columnForPartitioning); |
| query.append(" >= "); |
| query.append(offset != null ? offset : "0"); |
| if (limit != null) { |
| query.append(" AND "); |
| query.append(columnForPartitioning); |
| query.append(" < "); |
| query.append((offset == null ? 0 : offset) + limit); |
| } |
| } |
| } |
| if (!StringUtils.isEmpty(orderByClause) && StringUtils.isEmpty(columnForPartitioning)) { |
| query.append(" ORDER BY "); |
| query.append(orderByClause); |
| } |
| if (nestedSelect) { |
| query.append(") a"); |
| long offsetVal = 0; |
| if (offset != null) { |
| offsetVal = offset; |
| } |
| if (limit != null) { |
| query.append(" WHERE ROWNUM <= "); |
| query.append(offsetVal + limit); |
| } |
| query.append(") WHERE rnum > "); |
| query.append(offsetVal); |
| } |
| |
| return query.toString(); |
| } |
| |
| @Override |
| public String getTableAliasClause(String tableName) { |
| return tableName; |
| } |
| } |