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/* Licensed 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.activiti.engine.query;

import java.util.List;

import org.activiti.engine.ActivitiException;
import org.activiti.engine.api.internal.Internal;

/**
 * Describes basic methods for doing native queries
 *
 */
@Internal
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 ActivitiException
   *           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);
}