databasepolicy.java

把java对象映射成数据库表中的一条记录

/*
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 * License for the specific language governing rights and limitations under
 * the License.
 *
 * The Original Code is jRelationalFramework.
 *
 * The Initial Developer of the Original Code is is.com.
 * Portions created by is.com are Copyright (C) 2000 is.com.
 * All Rights Reserved.
 *
 * Contributor(s): Jonathan Carlson ([e-mail])
 * Contributor(s): ____________________________________
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License (the "GPL") or the GNU Lesser General
 * Public license (the "LGPL"), in which case the provisions of the GPL or
 * LGPL are applicable instead of those above.  If you wish to allow use of
 * your version of this file only under the terms of either the GPL or LGPL
 * and not to allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and replace them
 * with the notice and other provisions required by either the GPL or LGPL
 * License.  If you do not delete the provisions above, a recipient may use
 * your version of this file under either the MPL or GPL or LGPL License.
 *
 */
package com.is.jrf;


import com.is.util.sql.JDBCHelper;

import java.sql.Timestamp;
import java.sql.SQLException;


/**
 * This is an interface used to provide database specific behavior.  An
 * implementer of this is referenced by the AbstractDomain.
 *
 * @see OracleDatabasePolicy
 * @see SQLServerSybaseDatabasePolicy
 */
public interface DatabasePolicy
  {

  /* ===============  Abstract Methods  =============== */


  /**
   * Return a SQL string to get the next sequence number for a table.  When
   * executed, this SQL should return a one column, one row result set with
   * an integer.
   *
   * @param tableName a value of type 'String'
   * @return a value of type 'String'
   */
  public String sequenceSQL(String tableName);


  /**
   * This method creates a sequence for the domain object.  If the sequence
   * already exists, it will be reset to the beginning (usually 0).
   *
   * @param domain a value of type 'AbstractDomain'
   * @param aJDBCHelper a value of type 'JDBCHelper'
   * @exception SQLException if an error occurs
   */
  public void createSequence(AbstractDomain domain,
                             JDBCHelper aJDBCHelper)
          throws SQLException;


  /**
   * This should return the string value (function name) to put into the SQL
   * to tell the database to insert the current timestamp.
   *
   * @return a value of type 'String'
   */
  public String timestampFunction();


  /**
   * The return value should be in the string format that the database
   * recognizes as a timestamp.
   *
   * @param ts a value of type 'Timestamp'
   * @return a value of type 'String'
   */
  public String formatTimestamp(Timestamp ts);


  /**
   * The result of this is used in SQL.  This will format only the date
   * (not the time portion)
   *
   * @param sqlDate a value of type 'java.sql.Date'
   * @return a value of type 'String'
   */
  public String formatDate(java.sql.Date sqlDate);


  /**
   * This should return the the SQL to use to have the database
   * return the current timestamp.
   *
   * @return a value of type 'String'
   */
  public String currentTimestampSQL();


  /**
   *  auto-increment means that upon insertion, the integer column is
   *  automatically given a unique id by the dbms.
   *
   *  The auto-increment methods were added for InstantDB, HypsersonicSQL,
   *  and any other database that uses this instead of traditional
   *  sequencing methods that occur before insertion.
   */
  public String autoIncrementIdentifier();


  public Long findAutoIncrementId(String tableName,
                                  String columnName,
                                  JDBCHelper aJDBCHelper);


  /**
   * Return a string of a name-value pair that represents an SQL outer join
   * that can be used in a WHERE clause.
   * i.e. The result would look like this for Oracle: 'Tbl1.Id=Tbl2.Id(+)'
   *
   * @param mainTableColumn a value of type 'String'
   * @param joinTableColumn a value of type 'String'
   * @return a value of type 'String'
   */
  public abstract String outerWhereJoin(String mainTableColumn,
                                        String joinTableColumn);


  /**
   * This method used when building SQL for creating a table.
   *
   * @return a value of type 'String'
   */
  public String timestampColumnType();


  } // DatabasePolicy