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/*
 * Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
 * under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright
 * ownership. Camunda licenses this file to you under the Apache License,
 * Version 2.0; 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.camunda.bpm.engine.query;

import java.util.List;

import org.camunda.bpm.engine.ProcessEngineException;

/**
 * Describes basic methods for doing native queries
 * 
 * @author Bernd Ruecker (camunda)
 */
public interface NativeQuery, U extends Object> {

  /**
   * Hand in the SQL statement you want to execute. BEWARE: if you need a count you have to hand in a count() statement
   * yourself, otherwise the result will be treated as lost of Activiti entities.
   * 
   * If you need paging you have to insert the pagination code yourself. We skipped doing this for you
   * as this is done really different on some databases (especially MS-SQL / DB2)
   */
  T sql(String selectClause);
  
  /**
   * Add parameter to be replaced in query for index, e.g. :param1, :myParam, ...
   */
  T parameter(String name, Object value);

  /** Executes the query and returns the number of results */
  long count();

  /**
   * Executes the query and returns the resulting entity or null if no
   * entity matches the query criteria.
   * @throws ProcessEngineException when the query results in more than one
   * entities.
   */
  U singleResult();

  /** Executes the query and get a list of entities as the result. */
  List list();

  /** Executes the query and get a list of entities as the result. */
  List listPage(int firstResult, int maxResults);
}