dbutils.java

来自「Weka」· Java 代码 · 共 79 行

/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 * DbUtils.java
 * Copyright (C) 2005 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.gui.sql;

import weka.experiment.DatabaseUtils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * A little bit extended DatabaseUtils class.<p>
 * Note: needs at least HSQLDB 1.7.3.3 to work, older versions do not support
 * Cursors that can also move backwards - see <code>execute(String)</code>.
 *
 * @see       DatabaseUtils
 * @see       #execute(String)
 * @author    FracPete (fracpete at waikato dot ac dot nz)
 * @version   $Revision: 1.2 $
 */
public class DbUtils
  extends DatabaseUtils {

  /** for serialization */
  private static final long serialVersionUID = 103748569037426479L;
  
  /**
   * initializes the object
   * @throws Exception      in case something goes wrong in the init of the
   *                        DatabaseUtils constructor
   * @see     DatabaseUtils
   */
  public DbUtils() throws Exception {
    super();
  }

  /**
   * Executes a SQL query. Modified to allow forward and backward scrolling.
   *
   * @param query the SQL query
   * @return true if the query generated results
   * @exception SQLException if an error occurs
   */
  public boolean execute(String query) throws SQLException {
    m_PreparedStatement = m_Connection.prepareStatement(
        query, ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
    return(m_PreparedStatement.execute());
  }


  /**
   * returns the current database connection
   * @return        the current connection instance
   */
  public Connection getConnection() {
    return m_Connection;
  }
}