~maria-captains/mariadb-java-client/trunk : contents of src/main/java/org/mariadb/jdbc/MySQLStatement.java at revision 518

~maria-captains/mariadb-java-client/trunk : (revision 518)
/*
MariaDB Client for Java

Copyright (c) 2012 Monty Program Ab.

This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free
Software Foundation; either version 2.1 of the License, or (at your option)
any later version.

This library 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 Lesser General Public License
for more details.

You should have received a copy of the GNU Lesser General Public License along
with this library; if not, write to Monty Program Ab info@montyprogram.com.

This particular MariaDB Client for Java file is work
derived from a Drizzle-JDBC. Drizzle-JDBC file which is covered by subject to
the following copyright and notice provisions:

Copyright (c) 2009-2011, Marcus Eriksson

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice, this list
of conditions and the following disclaimer.

Redistributions in binary form must reproduce the above copyright notice, this
list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.

Neither the name of the driver nor the names of its contributors may not be
used to endorse or promote products derived from this software without specific
prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS  AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
OF SUCH DAMAGE.
*/

package org.mariadb.jdbc;

import org.mariadb.jdbc.internal.SQLExceptionMapper;
import org.mariadb.jdbc.internal.common.QueryException;
import org.mariadb.jdbc.internal.common.Utils;
import org.mariadb.jdbc.internal.common.query.MySQLQuery;
import org.mariadb.jdbc.internal.common.query.Query;
import org.mariadb.jdbc.internal.common.queryresults.ModifyQueryResult;
import org.mariadb.jdbc.internal.common.queryresults.QueryResult;
import org.mariadb.jdbc.internal.common.queryresults.ResultSetType;
import org.mariadb.jdbc.internal.mysql.MySQLProtocol;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.*;


public class MySQLStatement implements Statement {
    /**
     * the protocol used to talk to the server.
     */
    private final MySQLProtocol protocol;
    /**
     * the  Connection object.
     */
    protected MySQLConnection connection;


    /**
     * The actual query result.
     */
    private QueryResult queryResult;
    /**
     * are warnings cleared?
     */
    private boolean warningsCleared;


    private int queryTimeout;
    private boolean escapeProcessing;
    private int fetchSize;
    private int maxRows;
    boolean  isClosed;
    private static volatile Timer timer;
    private TimerTask timerTask;
    boolean isTimedout;
    volatile boolean executing;

    List<String> batchQueries;
    Queue<Object> cachedResultSets;
    private boolean isRewriteable = true;
    private String firstRewrite = null;


    public boolean isStreaming() {
        return fetchSize == Integer.MIN_VALUE;
    }

    /**
     * Creates a new Statement.
     * @param connection   the connection to return in getConnection.
     */

    public MySQLStatement(MySQLConnection connection) {
        this.protocol = connection.getProtocol();
        this.connection = connection;
        this.escapeProcessing = true;
        cachedResultSets = new LinkedList<Object>();

    }

    /**
     * returns the protocol.
     *
     * @return the protocol used.
     */
    public MySQLProtocol getProtocol() {
        return protocol;
    }

    private static Timer getTimer() {
        Timer result = timer;
        if (result == null) {
            synchronized(MySQLStatement.class) {
                result = timer;
                if (result == null) {
                    timer = result = new Timer("MariaDB-JDBC-Timer", true);
                }
            }
        }
        return result;
    }
    
    // Part of query prolog - setup timeout timer
    private void setTimerTask() {
    	assert(timerTask == null);
        timerTask = new TimerTask() {
             @Override
             public void run() {
                  try {
                      isTimedout = true;
                      protocol.cancelCurrentQuery();
                  } catch (Throwable e) {	
                  }  
             }
         };
         getTimer().schedule(timerTask, queryTimeout*1000);
    }
    
    // Part of query prolog - check if connection is broken and reconnect
    private void checkReconnect() throws SQLException {
        if (protocol.shouldReconnect()) {
             try {
                 protocol.connect();
             } catch (QueryException qe) {
                 SQLExceptionMapper.throwException(qe, connection, this);
             }
         }  else if (protocol.shouldTryFailback()) {
             try {
                 protocol.reconnectToMaster();
             } catch (Exception e) {
                 // Do nothing
             }
         }
    }
    
    void executeQueryProlog() throws SQLException{
        if (isClosed()) {
            throw new SQLException("execute() is called on closed statement");
        }
        checkReconnect();
        if (protocol.isClosed()){
            throw new SQLException("execute() is called on closed connection");     
        }
        if (protocol.hasUnreadData()) {
            throw new  SQLException("There is an open result set on the current connection, "+
                    "which must be closed prior to executing a query");
        }
        if (protocol.hasMoreResults()) {
            // Skip remaining result sets. CallableStatement might return many of them  - 
        	// not only the "select" result sets, but also the "update" results
            while(getMoreResults(true)) {
            }
        }

        cachedResultSets.clear();
        MySQLConnection conn = (MySQLConnection)getConnection();
        conn.reenableWarnings();
        
        try {
            protocol.setMaxRows(maxRows);
        } catch(QueryException qe) {
            SQLExceptionMapper.throwException(qe, connection, this);
        }
        
        if (queryTimeout != 0) {
	    	setTimerTask();
        }
    }

    private void cacheMoreResults() {

        if (isStreaming())
            return;
        QueryResult saveResult = queryResult;
        for(;;) {
            try {
                if (getMoreResults(false)) {
                   cachedResultSets.add(queryResult);
                } else {
                    break;
                }
            } catch(SQLException e) {
               cachedResultSets.add(e);
               break;
            }
        }
        queryResult = saveResult;
    }



    /*
     Reset timeout after query, re-throw  SQL  exception
    */
    private void executeQueryEpilog(QueryException e, Query query) throws SQLException{

        if (timerTask != null) {
          timerTask.cancel();
          timerTask = null;
        }

        if (isTimedout)  {
            isTimedout = false;
            e = new QueryException("Query timed out", 1317, "JZ0002", e);
        }
        
        if (e == null)
        	return;
        
        /* Include query into exception message, if dumpQueriesOnException is true, 
         * or on SQL syntax error (MySQL error code 1064). 
         * 
         * If SQL query is too long, truncate it to reasonable (for exception messages) 
         * length. 
         */
        if (protocol.getInfo().getProperty("dumpQueriesOnException", "false").equalsIgnoreCase("true") 
        		|| e.getErrorCode() == 1064 ) {
        	String queryString = query.toString();
            if (queryString.length() > 4096) {
        	    queryString = queryString.substring(0, 4096);
            }
            e.setMessage(e.getMessage()+ "\nQuery is:\n" + queryString);
        }
        	
         SQLExceptionMapper.throwException(e, connection, this);
    }

    /**
     * executes a query.
     *
     * @param query the query
     * @return true if there was a result set, false otherwise.
     * @throws SQLException
     */
     protected boolean execute(Query query) throws SQLException {
    	//System.out.println(query);
        synchronized (protocol) {
        	if (protocol.activeResult != null) {
                protocol.activeResult.close();
            }
            executing = true;
            QueryException exception = null;
            executeQueryProlog();
            try {
                queryResult = protocol.executeQuery(query, isStreaming());
                cacheMoreResults();
                return (queryResult.getResultSetType() == ResultSetType.SELECT);
            } catch (QueryException e) {
              exception = e;
              return false;
            } finally {
                executeQueryEpilog(exception, query);
                executing = false;
            }
        }
    }

     /**
     * executes a select query.
     *
     * @param query the query to send to the server
     * @return a result set
     * @throws SQLException if something went wrong
     */
    protected ResultSet executeQuery(Query query) throws SQLException {
        if (execute(query)) {
            return getResultSet();
        }
        //throw new SQLException("executeQuery() with query '" + query +"' did not return a result set");
        return MySQLResultSet.EMPTY;
    }

    /**
     * Executes an update.
     *
     * @param query the update query.
     * @return update count
     * @throws SQLException if the query could not be sent to server.
     */
    protected int executeUpdate(Query query) throws SQLException {
        if (execute(query))
            return 0;
        return getUpdateCount();
    }

    private Query stringToQuery(String queryString) throws SQLException {
        if (escapeProcessing) {
            queryString = Utils.nativeSQL(queryString,connection.noBackslashEscapes);
        }
        return new MySQLQuery(queryString);
    }


    /**
     * executes a query.
     *
     * @param queryString the query
     * @return true if there was a result set, false otherwise.
     * @throws SQLException
     */
    public boolean execute(String queryString) throws SQLException {
        return execute(stringToQuery(queryString));
    }

    /**
     * Executes an update.
     *
     * @param queryString the update query.
     * @return update count
     * @throws SQLException if the query could not be sent to server.
     */
    public int executeUpdate(String queryString) throws SQLException {
        return executeUpdate(stringToQuery(queryString));
    }


     /**
     * executes a select query.
     *
     * @param queryString the query to send to the server
     * @return a result set
     * @throws SQLException if something went wrong
     */
    public ResultSet executeQuery(String queryString) throws SQLException {
        return executeQuery(stringToQuery(queryString));
    }


    /**
     * Releases this <code>Statement</code> object's database and JDBC resources immediately instead of waiting for this
     * to happen when it is automatically closed. It is generally good practice to release resources as soon as you are
     * finished with them to avoid tying up database resources.
     * <p/>
     * Calling the method <code>close</code> on a <code>Statement</code> object that is already closed has no effect.
     * <p/>
     * <B>Note:</B>When a <code>Statement</code> object is closed, its current <code>ResultSet</code> object, if one
     * exists, is also closed.
     *
     * @throws java.sql.SQLException if a database access error occurs
     */
    public void close() throws SQLException {

        if (queryResult != null) {
            queryResult.close();
            queryResult = null;
        }
        // No possible future use for the cached results, so these can be cleared
        // This makes the cache eligible for garbage collection earlier if the statement is not
        // immediately garbage collected
        cachedResultSets.clear();
        if (isStreaming()) {
            synchronized (protocol) {
                    // Skip all outstanding result sets
                    while(getMoreResults(true)) {
                }
            }
        }
        isClosed = true;
    }

    /**
     * Retrieves the maximum number of bytes that can be returned for character and binary column values in a
     * <code>ResultSet</code> object produced by this <code>Statement</code> object. This limit applies only to
     * <code>BINARY</code>, <code>VARBINARY</code>, <code>LONGVARBINARY</code>, <code>CHAR</code>, <code>VARCHAR</code>,
     * <code>NCHAR</code>, <code>NVARCHAR</code>, <code>LONGNVARCHAR</code> and <code>LONGVARCHAR</code> columns.  If
     * the limit is exceeded, the excess data is silently discarded.
     *
     * @return the current column size limit for columns storing character and binary values; zero means there is no
     *         limit
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @see #setMaxFieldSize
     */
    public int getMaxFieldSize() throws SQLException {
        return 0;
    }

    /**
     * Sets the limit for the maximum number of bytes that can be returned for character and binary column values in a
     * <code>ResultSet</code> object produced by this <code>Statement</code> object.
     * <p/>
     * This limit applies only to <code>BINARY</code>, <code>VARBINARY</code>, <code>LONGVARBINARY</code>,
     * <code>CHAR</code>, <code>VARCHAR</code>, <code>NCHAR</code>, <code>NVARCHAR</code>, <code>LONGNVARCHAR</code> and
     * <code>LONGVARCHAR</code> fields.  If the limit is exceeded, the excess data is silently discarded. For maximum
     * portability, use values greater than 256.
     *
     * @param max the new column size limit in bytes; zero means there is no limit
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the condition max >= 0 is not satisfied
     * @see #getMaxFieldSize
     */
    public void setMaxFieldSize(final int max) throws SQLException {
        //we dont support max field sizes
    }

    /**
     * Retrieves the maximum number of rows that a <code>ResultSet</code> object produced by this <code>Statement</code>
     * object can contain.  If this limit is exceeded, the excess rows are silently dropped.
     *
     * @return the current maximum number of rows for a <code>ResultSet</code> object produced by this
     *         <code>Statement</code> object; zero means there is no limit
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @see #setMaxRows
     */
    public int getMaxRows() throws SQLException {
        return maxRows;
    }

    /**
     * Sets the limit for the maximum number of rows that any <code>ResultSet</code> object  generated by this
     * <code>Statement</code> object can contain to the given number. If the limit is exceeded, the excess rows are
     * silently dropped.
     *
     * @param max the new max rows limit; zero means there is no limit
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the condition max >= 0 is not satisfied
     * @see #getMaxRows
     */
    public void setMaxRows(final int max) throws SQLException {
        if (max < 0) {
            throw new SQLException("max rows is negative");
        }
        maxRows = max;
    }

    /**
     * Sets escape processing on or off. If escape scanning is on (the default), the driver will do escape substitution
     * before sending the SQL statement to the database.
     * <p/>
     * Note: Since prepared statements have usually been parsed prior to making this call, disabling escape processing
     * for <code>PreparedStatements</code> objects will have no effect.
     *
     * @param enable <code>true</code> to enable escape processing; <code>false</code> to disable it
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     */
    public void setEscapeProcessing(final boolean enable) throws SQLException {
        escapeProcessing = enable;
    }

    /**
     * Retrieves the number of seconds the driver will wait for a <code>Statement</code> object to execute. If the limit
     * is exceeded, a <code>SQLException</code> is thrown.
     *
     * @return the current query timeout limit in seconds; zero means there is no limit
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @see #setQueryTimeout
     */
    public int getQueryTimeout() throws SQLException {
        return queryTimeout;
    }

    /**
     * Sets the number of seconds the driver will wait for a <code>Statement</code> object to execute to the given
     * number of seconds. If the limit is exceeded, an <code>SQLException</code> is thrown. A JDBC driver must apply
     * this limit to the <code>execute</code>, <code>executeQuery</code> and <code>executeUpdate</code> methods. JDBC
     * driver implementations may also apply this limit to <code>ResultSet</code> methods (consult your driver vendor
     * documentation for details).
     *
     * @param seconds the new query timeout limit in seconds; zero means there is no limit
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the condition seconds >= 0 is not satisfied
     * @see #getQueryTimeout
     */
    public void setQueryTimeout(final int seconds) throws SQLException {
        this.queryTimeout = seconds;
    }

    /**
     * Sets the inputStream that will be used for the next execute that uses
     * "LOAD DATA LOCAL INFILE". The name specified as local file/URL will be
     * ignored.
     * 
     * @param inputStream
     */
    public void setLocalInfileInputStream(InputStream inputStream) {
    	protocol.setLocalInfileInputStream(inputStream);
    }
    
    /**
     * Cancels this <code>Statement</code> object if both the DBMS and driver support aborting an SQL statement. This
     * method can be used by one thread to cancel a statement that is being executed by another thread.
     *
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method
     */
    public void cancel() throws SQLException {
        try {
            if (!executing) {
                return;
            }
            protocol.cancelCurrentQuery();
        } catch (QueryException e) {
            SQLExceptionMapper.throwException(e, connection, this);

        }
        catch (IOException e) {
            // connection gone, query is definitely canceled
        }
    }

    /**
     * Retrieves the first warning reported by calls on this <code>Statement</code> object. Subsequent
     * <code>Statement</code> object warnings will be chained to this <code>SQLWarning</code> object.
     * <p/>
     * <p>The warning chain is automatically cleared each time a statement is (re)executed. This method may not be
     * called on a closed <code>Statement</code> object; doing so will cause an <code>SQLException</code> to be thrown.
     * <p/>
     * <P><B>Note:</B> If you are processing a <code>ResultSet</code> object, any warnings associated with reads on that
     * <code>ResultSet</code> object will be chained on it rather than on the <code>Statement</code> object that
     * produced it.
     *
     * @return the first <code>SQLWarning</code> object or <code>null</code> if there are no warnings
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     */
    public SQLWarning getWarnings() throws SQLException {
        if (!warningsCleared) {
            return this.connection.getWarnings();
        }
        return null;
    }

    /**
     * Clears all the warnings reported on this <code>Statement</code> object. After a call to this method, the method
     * <code>getWarnings</code> will return <code>null</code> until a new warning is reported for this
     * <code>Statement</code> object.
     *
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     */
    public void clearWarnings() throws SQLException {
        warningsCleared = true;
    }

    /**
     * Sets the SQL cursor name to the given <code>String</code>, which will be used by subsequent
     * <code>Statement</code> object <code>execute</code> methods. This name can then be used in SQL positioned update
     * or delete statements to identify the current row in the <code>ResultSet</code> object generated by this
     * statement.  If the database does not support positioned update/delete, this method is a noop.  To insure that a
     * cursor has the proper isolation level to support updates, the cursor's <code>SELECT</code> statement should have
     * the form <code>SELECT FOR UPDATE</code>.  If <code>FOR UPDATE</code> is not present, positioned updates may
     * fail.
     * <p/>
     * <P><B>Note:</B> By definition, the execution of positioned updates and deletes must be done by a different
     * <code>Statement</code> object than the one that generated the <code>ResultSet</code> object being used for
     * positioning. Also, cursor names must be unique within a connection.
     *
     * @param name the new cursor name, which must be unique within a connection
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method
     */
    public void setCursorName(final String name) throws SQLException {
        throw SQLExceptionMapper.getFeatureNotSupportedException("Cursors are not supported");
    }

    /**
     * gets the connection that created this statement
     *
     * @return the connection
     * @throws SQLException
     */
    public Connection getConnection() throws SQLException {
        return this.connection;
    }

    /**
     * Moves to this <code>Statement</code> object's next result, deals with any current <code>ResultSet</code>
     * object(s) according  to the instructions specified by the given flag, and returns <code>true</code> if the next
     * result is a <code>ResultSet</code> object.
     * <p/>
     * <P>There are no more results when the following is true: <PRE> // stmt is a Statement object
     * ((stmt.getMoreResults(current) == false) && (stmt.getUpdateCount() == -1)) </PRE>
     *
     * @param current one of the following <code>Statement</code> constants indicating what should happen to current
     *                <code>ResultSet</code> objects obtained using the method <code>getResultSet</code>:
     *                <code>Statement.CLOSE_CURRENT_RESULT</code>, <code>Statement.KEEP_CURRENT_RESULT</code>, or
     *                <code>Statement.CLOSE_ALL_RESULTS</code>
     * @return <code>true</code> if the next result is a <code>ResultSet</code> object; <code>false</code> if it is an
     *         update count or there are no more results
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the argument supplied is not one of the following:
     *                               <code>Statement.CLOSE_CURRENT_RESULT</code>, <code>Statement.KEEP_CURRENT_RESULT</code>
     *                               or <code>Statement.CLOSE_ALL_RESULTS</code>
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if <code>DatabaseMetaData.supportsMultipleOpenResults</code> returns
     *                               <code>false</code> and either <code>Statement.KEEP_CURRENT_RESULT</code> or
     *                               <code>Statement.CLOSE_ALL_RESULTS</code> are supplied as the argument.
     * @see #execute
     * @since 1.4
     */
    public boolean getMoreResults(final int current) throws SQLException {
        return getMoreResults();
    }

    /**
     * Retrieves any auto-generated keys created as a result of executing this <code>Statement</code> object. If this
     * <code>Statement</code> object did not generate any keys, an empty <code>ResultSet</code> object is returned.
     * <p/>
     * <p><B>Note:</B>If the columns which represent the auto-generated keys were not specified, the JDBC driver
     * implementation will determine the columns which best represent the auto-generated keys.
     *
     * @return a <code>ResultSet</code> object containing the auto-generated key(s) generated by the execution of this
     *         <code>Statement</code> object
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method
     * @since 1.4
     */
    public ResultSet getGeneratedKeys() throws SQLException {
        if (queryResult != null && queryResult.getResultSetType() == ResultSetType.MODIFY) {
            long insertId = ((ModifyQueryResult)queryResult).getInsertId();
            int updateCount = getUpdateCount();
            
            return MySQLResultSet.createGeneratedKeysResultSet(insertId, updateCount, connection);
        }
        return MySQLResultSet.EMPTY;
    }

    /**
     * Executes the given SQL statement and signals the driver with the given flag about whether the auto-generated keys
     * produced by this <code>Statement</code> object should be made available for retrieval.  The driver will ignore
     * the flag if the SQL statement is not an <code>INSERT</code> statement, or an SQL statement able to return
     * auto-generated keys (the list of such statements is vendor-specific).
     *
     * @param sql               an SQL Data Manipulation Language (DML) statement, such as <code>INSERT</code>,
     *                          <code>UPDATE</code> or <code>DELETE</code>; or an SQL statement that returns nothing,
     *                          such as a DDL statement.
     * @param autoGeneratedKeys a flag indicating whether auto-generated keys should be made available for retrieval;
     *                          one of the following constants: <code>Statement.RETURN_GENERATED_KEYS</code>
     *                          <code>Statement.NO_GENERATED_KEYS</code>
     * @return either (1) the row count for SQL Data Manipulation Language (DML) statements or (2) 0 for SQL statements
     *         that return nothing
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code>, the given SQL statement returns a <code>ResultSet</code>
     *                               object, or the given constant is not one of those allowed
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method with a constant of
     *                               Statement.RETURN_GENERATED_KEYS
     * @since 1.4
     */
    public int executeUpdate(final String sql, final int autoGeneratedKeys) throws SQLException {
        return executeUpdate(sql);
    }

    /**
     * Executes the given SQL statement and signals the driver that the auto-generated keys indicated in the given array
     * should be made available for retrieval.   This array contains the indexes of the columns in the target table that
     * contain the auto-generated keys that should be made available. The driver will ignore the array if the SQL
     * statement is not an <code>INSERT</code> statement, or an SQL statement able to return auto-generated keys (the
     * list of such statements is vendor-specific).
     *
     * @param sql           an SQL Data Manipulation Language (DML) statement, such as <code>INSERT</code>,
     *                      <code>UPDATE</code> or <code>DELETE</code>; or an SQL statement that returns nothing, such
     *                      as a DDL statement.
     * @param columnIndexes an array of column indexes indicating the columns that should be returned from the inserted
     *                      row
     * @return either (1) the row count for SQL Data Manipulation Language (DML) statements or (2) 0 for SQL statements
     *         that return nothing
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code>, the SQL statement returns a <code>ResultSet</code> object,
     *                               or the second argument supplied to this method is not an <code>int</code> array
     *                               whose elements are valid column indexes
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method
     * @since 1.4
     */
    public int executeUpdate(final String sql, final int[] columnIndexes) throws SQLException {
       return executeUpdate(sql);
    }

    /**
     * Executes the given SQL statement and signals the driver that the auto-generated keys indicated in the given array
     * should be made available for retrieval.   This array contains the names of the columns in the target table that
     * contain the auto-generated keys that should be made available. The driver will ignore the array if the SQL
     * statement is not an <code>INSERT</code> statement, or an SQL statement able to return auto-generated keys (the
     * list of such statements is vendor-specific).
     *
     * @param sql         an SQL Data Manipulation Language (DML) statement, such as <code>INSERT</code>,
     *                    <code>UPDATE</code> or <code>DELETE</code>; or an SQL statement that returns nothing, such as
     *                    a DDL statement.
     * @param columnNames an array of the names of the columns that should be returned from the inserted row
     * @return either the row count for <code>INSERT</code>, <code>UPDATE</code>, or <code>DELETE</code> statements, or
     *         0 for SQL statements that return nothing
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code>, the SQL statement returns a <code>ResultSet</code> object,
     *                               or the second argument supplied to this method is not a <code>String</code> array
     *                               whose elements are valid column names
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method
     * @since 1.4
     */
    public int executeUpdate(final String sql, final String[] columnNames) throws SQLException {
        return executeUpdate(sql);
    }

    /**
     * Executes the given SQL statement, which may return multiple results, and signals the driver that any
     * auto-generated keys should be made available for retrieval.  The driver will ignore this signal if the SQL
     * statement is not an <code>INSERT</code> statement, or an SQL statement able to return auto-generated keys (the
     * list of such statements is vendor-specific).
     * <p/>
     * In some (uncommon) situations, a single SQL statement may return multiple result sets and/or update counts.
     * Normally you can ignore this unless you are (1) executing a stored procedure that you know may return multiple
     * results or (2) you are dynamically executing an unknown SQL string.
     * <p/>
     * The <code>execute</code> method executes an SQL statement and indicates the form of the first result.  You must
     * then use the methods <code>getResultSet</code> or <code>getUpdateCount</code> to retrieve the result, and
     * <code>getMoreResults</code> to move to any subsequent result(s).
     *
     * @param sql               any SQL statement
     * @param autoGeneratedKeys a constant indicating whether auto-generated keys should be made available for retrieval
     *                          using the method <code>getGeneratedKeys</code>; one of the following constants:
     *                          <code>Statement.RETURN_GENERATED_KEYS</code> or <code>Statement.NO_GENERATED_KEYS</code>
     * @return <code>true</code> if the first result is a <code>ResultSet</code> object; <code>false</code> if it is an
     *         update count or there are no results
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the second parameter supplied to this method is not
     *                               <code>Statement.RETURN_GENERATED_KEYS</code> or <code>Statement.NO_GENERATED_KEYS</code>.
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method with a constant of
     *                               Statement.RETURN_GENERATED_KEYS
     * @see #getResultSet
     * @see #getUpdateCount
     * @see #getMoreResults
     * @see #getGeneratedKeys
     * @since 1.4
     */
    public boolean execute(final String sql, final int autoGeneratedKeys) throws SQLException {
        return execute(sql); // auto generated keys are always available
    }

    /**
     * Executes the given SQL statement, which may return multiple results, and signals the driver that the
     * auto-generated keys indicated in the given array should be made available for retrieval.  This array contains the
     * indexes of the columns in the target table that contain the auto-generated keys that should be made available.
     * The driver will ignore the array if the SQL statement is not an <code>INSERT</code> statement, or an SQL
     * statement able to return auto-generated keys (the list of such statements is vendor-specific).
     * <p/>
     * Under some (uncommon) situations, a single SQL statement may return multiple result sets and/or update counts.
     * Normally you can ignore this unless you are (1) executing a stored procedure that you know may return multiple
     * results or (2) you are dynamically executing an unknown SQL string.
     * <p/>
     * The <code>execute</code> method executes an SQL statement and indicates the form of the first result.  You must
     * then use the methods <code>getResultSet</code> or <code>getUpdateCount</code> to retrieve the result, and
     * <code>getMoreResults</code> to move to any subsequent result(s).
     *
     * @param sql           any SQL statement
     * @param columnIndexes an array of the indexes of the columns in the inserted row that should be  made available
     *                      for retrieval by a call to the method <code>getGeneratedKeys</code>
     * @return <code>true</code> if the first result is a <code>ResultSet</code> object; <code>false</code> if it is an
     *         update count or there are no results
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the elements in the <code>int</code> array passed to this
     *                               method are not valid column indexes
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method
     * @see #getResultSet
     * @see #getUpdateCount
     * @see #getMoreResults
     * @since 1.4
     */
    public boolean execute(final String sql, final int[] columnIndexes) throws SQLException {
        return execute(sql);
    }

    /**
     * Executes the given SQL statement, which may return multiple results, and signals the driver that the
     * auto-generated keys indicated in the given array should be made available for retrieval. This array contains the
     * names of the columns in the target table that contain the auto-generated keys that should be made available.  The
     * driver will ignore the array if the SQL statement is not an <code>INSERT</code> statement, or an SQL statement
     * able to return auto-generated keys (the list of such statements is vendor-specific).
     * <p/>
     * In some (uncommon) situations, a single SQL statement may return multiple result sets and/or update counts.
     * Normally you can ignore this unless you are (1) executing a stored procedure that you know may return multiple
     * results or (2) you are dynamically executing an unknown SQL string.
     * <p/>
     * The <code>execute</code> method executes an SQL statement and indicates the form of the first result.  You must
     * then use the methods <code>getResultSet</code> or <code>getUpdateCount</code> to retrieve the result, and
     * <code>getMoreResults</code> to move to any subsequent result(s).
     *
     * @param sql         any SQL statement
     * @param columnNames an array of the names of the columns in the inserted row that should be made available for
     *                    retrieval by a call to the method <code>getGeneratedKeys</code>
     * @return <code>true</code> if the next result is a <code>ResultSet</code> object; <code>false</code> if it is an
     *         update count or there are no more results
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the elements of the <code>String</code> array passed to
     *                               this method are not valid column names
     * @throws java.sql.SQLFeatureNotSupportedException
     *                               if the JDBC driver does not support this method
     * @see #getResultSet
     * @see #getUpdateCount
     * @see #getMoreResults
     * @see #getGeneratedKeys
     * @since 1.4
     */
    public boolean execute(final String sql, final String[] columnNames) throws SQLException {
        return execute(sql);
    }

    /**
     * Retrieves the result set holdability for <code>ResultSet</code> objects generated by this <code>Statement</code>
     * object.
     *
     * @return either <code>ResultSet.HOLD_CURSORS_OVER_COMMIT</code> or <code>ResultSet.CLOSE_CURSORS_AT_COMMIT</code>
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @since 1.4
     */
    public int getResultSetHoldability() throws SQLException {
        return ResultSet.HOLD_CURSORS_OVER_COMMIT;
    }

    /**
     * Retrieves whether this <code>Statement</code> object has been closed. A <code>Statement</code> is closed if the
     * method close has been called on it, or if it is automatically closed.
     *
     * @return true if this <code>Statement</code> object is closed; false if it is still open
     * @throws java.sql.SQLException if a database access error occurs
     * @since 1.6
     */
    public boolean isClosed() throws SQLException {
        return isClosed;
    }

    /**
     * Requests that a <code>Statement</code> be pooled or not pooled.  The value specified is a hint to the statement
     * pool implementation indicating whether the applicaiton wants the statement to be pooled.  It is up to the
     * statement pool manager as to whether the hint is used.
     * <p/>
     * The poolable value of a statement is applicable to both internal statement caches implemented by the driver and
     * external statement caches implemented by application servers and other applications.
     * <p/>
     * By default, a <code>Statement</code> is not poolable when created, and a <code>PreparedStatement</code> and
     * <code>CallableStatement</code> are poolable when created.
     * <p/>
     *
     * @param poolable requests that the statement be pooled if true and that the statement not be pooled if false
     *                 <p/>
     * @throws java.sql.SQLException if this method is called on a closed <code>Statement</code>
     *                               <p/>
     * @since 1.6
     */
    public void setPoolable(final boolean poolable) throws SQLException {

    }

    /**
     * Returns a  value indicating whether the <code>Statement</code> is poolable or not.
     * <p/>
     *
     * @return <code>true</code> if the <code>Statement</code> is poolable; <code>false</code> otherwise
     *         <p/>
     * @throws java.sql.SQLException if this method is called on a closed <code>Statement</code>
     *                               <p/>
     * @see java.sql.Statement#setPoolable(boolean) setPoolable(boolean)
     * @since 1.6
     *        <p/>
     */
    public boolean isPoolable() throws SQLException {
        return false;
    }


    public ResultSet getResultSet() throws SQLException {
        if (queryResult == null || queryResult.getResultSetType() != ResultSetType.SELECT) {
            return null; /* Result is an update count, or there are no more results */
        }
        return new MySQLResultSet(queryResult,this,protocol, connection.cal);
    }

    public int getUpdateCount() throws SQLException {
        if (queryResult == null || queryResult.getResultSetType() == ResultSetType.SELECT) {
            return -1;  /* Result comes from SELECT , or there are no more results */
        }
        return (int) ((ModifyQueryResult) queryResult).getUpdateCount();
    }


    private boolean getMoreResults(boolean streaming) throws SQLException {
        try {
            synchronized(protocol) {
                if (queryResult != null) {
                    queryResult.close();
                }

                queryResult = protocol.getMoreResults(streaming);
                if(queryResult == null) return false;
                warningsCleared = false;
                connection.reenableWarnings();
                return true;
            }
        } catch (QueryException e) {
            SQLExceptionMapper.throwException(e, connection, this);
            return false;
        }
    }

    /**
     * Moves to this <code>Statement</code> object's next result, returns <code>true</code> if it is a
     * <code>ResultSet</code> object, and implicitly closes any current <code>ResultSet</code> object(s) obtained with
     * the method <code>getResultSet</code>.
     * <p/>
     * <P>There are no more results when the following is true: <PRE> // stmt is a Statement object
     * ((stmt.getMoreResults() == false) && (stmt.getUpdateCount() == -1)) </PRE>
     *
     * @return <code>true</code> if the next result is a <code>ResultSet</code> object; <code>false</code> if it is an
     *         update count or there are no more results
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @see #execute
     */
    public boolean getMoreResults() throws SQLException {
         if (!isStreaming()) {
            /* return pre-cached result set, if available */
            if(cachedResultSets.isEmpty()) {
                queryResult = null;
                return false;
            }
            
            Object o = cachedResultSets.remove();
            if (o instanceof SQLException)
                throw (SQLException)o;

            queryResult = (QueryResult)o;
            return true;
        }
        return getMoreResults(false);
    }

    /**
     * Gives the driver a hint as to the direction in which rows will be processed in <code>ResultSet</code> objects
     * created using this <code>Statement</code> object.  The default value is <code>ResultSet.FETCH_FORWARD</code>.
     * <p/>
     * Note that this method sets the default fetch direction for result sets generated by this <code>Statement</code>
     * object. Each result set has its own methods for getting and setting its own fetch direction.
     *
     * @param direction the initial direction for processing rows
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the given direction is not one of
     *                               <code>ResultSet.FETCH_FORWARD</code>, <code>ResultSet.FETCH_REVERSE</code>, or
     *                               <code>ResultSet.FETCH_UNKNOWN</code>
     * @see #getFetchDirection
     * @since 1.2
     */
    public void setFetchDirection(final int direction) throws SQLException {

    }

    /**
     * Retrieves the direction for fetching rows from database tables that is the default for result sets generated from
     * this <code>Statement</code> object. If this <code>Statement</code> object has not set a fetch direction by
     * calling the method <code>setFetchDirection</code>, the return value is implementation-specific.
     *
     * @return the default fetch direction for result sets generated from this <code>Statement</code> object
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @see #setFetchDirection
     * @since 1.2
     */
    public int getFetchDirection() throws SQLException {
        return ResultSet.FETCH_FORWARD;
    }

    /**
     * Gives the JDBC driver a hint as to the number of rows that should be fetched from the database when more rows are
     * needed for <code>ResultSet</code> objects genrated by this <code>Statement</code>. If the value specified is
     * zero, then the hint is ignored. The default value is zero.
     *
     * @param rows the number of rows to fetch
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the condition  <code>rows >= 0</code> is not satisfied.
     * @see #getFetchSize
     * @since 1.2
     */
    public void setFetchSize(final int rows) throws SQLException {
        if (rows < 0 && rows != Integer.MIN_VALUE)
            throw new SQLException("invalid fetch size");
         this.fetchSize = rows;
    }

    /**
     * Retrieves the number of result set rows that is the default fetch size for <code>ResultSet</code> objects
     * generated from this <code>Statement</code> object. If this <code>Statement</code> object has not set a fetch size
     * by calling the method <code>setFetchSize</code>, the return value is implementation-specific.
     *
     * @return the default fetch size for result sets generated from this <code>Statement</code> object
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @see #setFetchSize
     * @since 1.2
     */
    public int getFetchSize() throws SQLException {
        return this.fetchSize;
    }

    /**
     * Retrieves the result set concurrency for <code>ResultSet</code> objects generated by this <code>Statement</code>
     * object.
     *
     * @return either <code>ResultSet.CONCUR_READ_ONLY</code> or <code>ResultSet.CONCUR_UPDATABLE</code>
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @since 1.2
     */
    public int getResultSetConcurrency() throws SQLException {
        return ResultSet.CONCUR_READ_ONLY;
    }

    /**
     * Retrieves the result set type for <code>ResultSet</code> objects generated by this <code>Statement</code>
     * object.
     *
     * @return one of <code>ResultSet.TYPE_FORWARD_ONLY</code>, <code>ResultSet.TYPE_SCROLL_INSENSITIVE</code>, or
     *         <code>ResultSet.TYPE_SCROLL_SENSITIVE</code>
     * @throws java.sql.SQLException if a database access error occurs or this method is called on a closed
     *                               <code>Statement</code>
     * @since 1.2
     */
    public int getResultSetType() throws SQLException {
        // TODO: this will change when the async protocol is implemented
        return ResultSet.TYPE_SCROLL_INSENSITIVE;
    }

    /**
     * Adds the given SQL command to the current list of commmands for this <code>Statement</code> object. The commands
     * in this list can be executed as a batch by calling the method <code>executeBatch</code>.
     * <p/>
     *
     * @param sql typically this is a SQL <code>INSERT</code> or <code>UPDATE</code> statement
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the driver does not support batch updates
     * @see #executeBatch
     * @see java.sql.DatabaseMetaData#supportsBatchUpdates
     * @since 1.2
     */
    public void addBatch(final String sql) throws SQLException {
        if (batchQueries == null) {
            batchQueries = new ArrayList<String>();
        }
        batchQueries.add(sql);
        isInsertRewriteable(sql);
    }
    
    /**
     * Parses the sql string to understand whether it is compatible with rewritten batches.
     * @param sql the sql string
     */
    private void isInsertRewriteable(String sql) {
    	if (!isRewriteable) {
    		return;
    	}
    	int index = getInsertIncipit(sql);
    	if (index == -1) {
    		isRewriteable = false;
    		return;
    	}
    	if (firstRewrite == null) {
    		firstRewrite = sql.substring(0, index);
    	}
    	boolean isRewrite = sql.startsWith(firstRewrite);
        if (isRewrite) {
        	isRewriteable = isRewriteable && true;
        }
    }
    
    /**
     * Parses the input string to understand if it is an INSERT statement.
     * Returns the position of the round bracket after the VALUE(S) SQL keyword,
     * or -1 if it cannot understand it is an INSERT statement.
     * Multiple statements cannot be parsed.
     * @param sql the input SQL statement
     * @return the position of the round bracket after the VALUE(S) SQL keyword,
     * or -1 if it cannot be parsed as an INSERT statement
     */
    protected int getInsertIncipit(String sql) {
    	String sqlUpper = sql.toUpperCase();
    	if (! sqlUpper.startsWith("INSERT")
    			|| sqlUpper.indexOf(";") != -1) {
    		return -1;
    	}
    	int idx = sqlUpper.indexOf(" VALUE");
    	int index = sqlUpper.indexOf("(", idx);
    	return index;
    }
    
    /**
     * If the batch array contains only rewriteable sql strings, returns the rewritten statement.
     * @return the rewritten statement
     */
    private String rewrittenBatch() {
    	StringBuilder result = null;
    	if(isRewriteable) {
    		result = new StringBuilder("");
    		result.append(firstRewrite);
    		for (String query : batchQueries) {
    			result.append(query.substring(getInsertIncipit(query)));
    			result.append(",");
    		}
    		result.deleteCharAt(result.length() - 1);
    	}
    	return (result == null ? null : result.toString());
    }


    /**
     * Empties this <code>Statement</code> object's current list of SQL commands.
     * <p/>
     *
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the driver does not support batch updates
     * @see #addBatch
     * @see java.sql.DatabaseMetaData#supportsBatchUpdates
     * @since 1.2
     */
    public void clearBatch() throws SQLException {
        if (batchQueries != null) {
            batchQueries.clear();
        }
        firstRewrite = null;
        isRewriteable = true;
    }

    /**
     * Submits a batch of commands to the database for execution and if all commands execute successfully, returns an
     * array of update counts. The <code>int</code> elements of the array that is returned are ordered to correspond to
     * the commands in the batch, which are ordered according to the order in which they were added to the batch. The
     * elements in the array returned by the method <code>executeBatch</code> may be one of the following: <OL> <LI>A
     * number greater than or equal to zero -- indicates that the command was processed successfully and is an update
     * count giving the number of rows in the database that were affected by the command's execution <LI>A value of
     * <code>SUCCESS_NO_INFO</code> -- indicates that the command was processed successfully but that the number of rows
     * affected is unknown
     * <p/>
     * If one of the commands in a batch update fails to execute properly, this method throws a
     * <code>BatchUpdateException</code>, and a JDBC driver may or may not continue to process the remaining commands in
     * the batch.  However, the driver's behavior must be consistent with a particular DBMS, either always continuing to
     * process commands or never continuing to process commands.  If the driver continues processing after a failure,
     * the array returned by the method <code>BatchUpdateException.getUpdateCounts</code> will contain as many elements
     * as there are commands in the batch, and at least one of the elements will be the following:
     * <p/>
     * <LI>A value of <code>EXECUTE_FAILED</code> -- indicates that the command failed to execute successfully and
     * occurs only if a driver continues to process commands after a command fails </OL>
     * <p/>
     * The possible implementations and return values have been modified in the Java 2 SDK, Standard Edition, version
     * 1.3 to accommodate the option of continuing to proccess commands in a batch update after a
     * <code>BatchUpdateException</code> obejct has been thrown.
     *
     * @return an array of update counts containing one element for each command in the batch.  The elements of the
     *         array are ordered according to the order in which commands were added to the batch.
     * @throws java.sql.SQLException if a database access error occurs, this method is called on a closed
     *                               <code>Statement</code> or the driver does not support batch statements. Throws
     *                               {@link java.sql.BatchUpdateException} (a subclass of <code>SQLException</code>) if
     *                               one of the commands sent to the database fails to execute properly or attempts to
     *                               return a result set.
     * @see #addBatch
     * @see java.sql.DatabaseMetaData#supportsBatchUpdates
     * @since 1.3
     */
    public int[] executeBatch() throws SQLException {
        if (batchQueries == null)
            return new int[0];

        int[] ret = new int[batchQueries.size()];
        int i = 0;
        try {
        	synchronized (this.protocol) {
        		if (getProtocol().getInfo().getProperty("rewriteBatchedStatements") != null
        				&& "true".equalsIgnoreCase(getProtocol().getInfo().getProperty("rewriteBatchedStatements"))) {
        			ret = executeBatchAsMultiQueries();
        		} else {
        			for(; i < batchQueries.size(); i++)  {
        				execute(batchQueries.get(i));
        				int updateCount = getUpdateCount();
        				if (updateCount == -1) {
        					ret[i] = SUCCESS_NO_INFO;
        				} else {
        					ret[i] = updateCount;
        				}
        			}
        		}
        	}
        } catch (SQLException sqle) {
            throw new BatchUpdateException(sqle.getMessage(), sqle.getSQLState(),Arrays.copyOf(ret, i), sqle);
        } finally {
            clearBatch();
        }
        return ret;
    }
    
    /**
	 * Builds a new statement which contains the batched Statements and executes it.
	 * @return an array of update counts containing one element for each command in the batch.
	 *  The elements of the array are ordered according to the order in which commands were added to the batch.
	 * @throws SQLException
	 */
	private int[] executeBatchAsMultiQueries() throws SQLException {
		int i = 0;
		StringBuilder stringBuilder = new StringBuilder();
		String rewrite = rewrittenBatch();
		if (rewrite != null) {
			stringBuilder.append(rewrite);
			i++;
		} else {
			for (; i < batchQueries.size(); i++) {
				stringBuilder.append(batchQueries.get(i) + ";");
			}
		}
		Statement ps = connection.createStatement();
		ps.execute(stringBuilder.toString());
		return getUpdateCounts(ps, i);
	}
	/**
	 * Retrieves the update counts for the batched statements rewritten as
	 * a multi query. The rewritten statement must have been executed already.
	 * @param statement the rewritten statement
	 * @return an array of update counts containing one element for each command in the batch.
	 *  The elements of the array are ordered according to the order in which commands were added to the batch.
	 * @throws SQLException
	 */
	protected int[] getUpdateCounts(Statement statement, int size) throws SQLException {
		int[] result = new int[size];
		int updateCount;
		for (int count=0; count<size; count++) {
			updateCount = statement.getUpdateCount();
            if (updateCount == -1) {
                result[count] = SUCCESS_NO_INFO;
            } else {
                result[count] = updateCount;
            }
            statement.getMoreResults();
		}
		return result;
	}

    /**
     * Returns an object that implements the given interface to allow access to non-standard methods, or standard
     * methods not exposed by the proxy.
     * <p/>
     * If the receiver implements the interface then the result is the receiver or a proxy for the receiver. If the
     * receiver is a wrapper and the wrapped object implements the interface then the result is the wrapped object or a
     * proxy for the wrapped object. Otherwise return the the result of calling <code>unwrap</code> recursively on the
     * wrapped object or a proxy for that result. If the receiver is not a wrapper and does not implement the interface,
     * then an <code>SQLException</code> is thrown.
     *
     * @param iface A Class defining an interface that the result must implement.
     * @return an object that implements the interface. May be a proxy for the actual implementing object.
     * @throws java.sql.SQLException If no object found that implements the interface
     * @since 1.6
     */
    @SuppressWarnings("unchecked")
	public <T> T unwrap(final Class<T> iface) throws SQLException {
    	try {
    		if (isWrapperFor(iface)) {
    			return (T)this;
    			} else {
    				throw new SQLException("The receiver is not a wrapper and does not implement the interface");
    			}
    		} catch (Exception e) {
    			throw new SQLException("The receiver is not a wrapper and does not implement the interface");
    		}
    	}

    /**
     * Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an
     * object that does. Returns false otherwise. If this implements the interface then return true, else if this is a
     * wrapper then return the result of recursively calling <code>isWrapperFor</code> on the wrapped object. If this
     * does not implement the interface and is not a wrapper, return false. This method should be implemented as a
     * low-cost operation compared to <code>unwrap</code> so that callers can use this method to avoid expensive
     * <code>unwrap</code> calls that may fail. If this method returns true then calling <code>unwrap</code> with the
     * same argument should succeed.
     *
     * @param interfaceOrWrapper a Class defining an interface.
     * @return true if this implements the interface or directly or indirectly wraps an object that does.
     * @throws java.sql.SQLException if an error occurs while determining whether this is a wrapper for an object with
     *                               the given interface.
     * @since 1.6
     */
    public boolean isWrapperFor(final Class<?> interfaceOrWrapper) throws SQLException {
        return interfaceOrWrapper.isInstance(this);
    }


    /**
     * returns the query result.
     *
     * @return the queryresult
     */
    protected QueryResult getQueryResult() {
        return queryResult;
    }

    /**
     * sets the current query result
     *
     * @param result
     */
    protected void setQueryResult(final QueryResult result) {
        this.queryResult = result;
    }

	public void closeOnCompletion() throws SQLException {
		// TODO Auto-generated method stub
		
	}

	public boolean isCloseOnCompletion() throws SQLException {
		// TODO Auto-generated method stub
		return false;
	}

    public static void unloadDriver() {
        if (timer != null)
            timer.cancel();
    }
}