HSQLDB example source code file (jdbcStatement.java)

This example HSQLDB source code file (jdbcStatement.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - HSQLDB tags/keywords

batchupdateexception, connection, hsqlexception, hsqlexception, jdbc, object, result, result, resultset, resultset, sql, sqlexception, sqlexception, sqlwarning, statement, string

The HSQLDB jdbcStatement.java source code

/* Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * 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 HSQL Development Group nor the names of its
 * contributors may 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 HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * 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.hsqldb.jdbc;

//#ifdef JAVA2
import java.sql.BatchUpdateException;

//#endif JAVA2
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.Statement;

import org.hsqldb.HsqlException;
import org.hsqldb.Result;
import org.hsqldb.ResultConstants;
import org.hsqldb.Trace;
import org.hsqldb.Types;

// fredt@users 20020320 - patch 1.7.0 - JDBC 2 support and error trapping
// JDBC 2 methods can now be called from jdk 1.1.x - see javadoc comments
// SCROLL_INSENSITIVE and FORWARD_ONLY types for ResultSet are now supported
// boucherb@users 20020509 - added "throws SQLException" to all methods where
// it was missing here but specified in the java.sql.Statement interface,
// updated generic documentation to JDK 1.4, and added JDBC3 methods and docs
// boucherb@users and fredt@users - 20020505 extensive review and update
// of docs and behaviour to comply with java.sql specification
// fredt@users 20030620 - patch 1.7.2 - rewritten and simplified
// boucherb@users 200404xx - javadoc updates toward 1.7.2 final

/**
 * <!-- start generic documentation -->
 * The object used for executing a static SQL statement
 * and returning the results it produces.
 * <P>
 * By default, only one <code>ResultSet object per Statement
 * object can be open at the same time. Therefore, if the reading of one
 * <code>ResultSet object is interleaved
 * with the reading of another, each must have been generated by
 * different <code>Statement objects. All execution methods in the
 * <code>Statement interface implicitly close a statment's current
 * <code>ResultSet object if an open one exists.

 * <!-- end generic documentation-->
 *
 * <!-- start release-specific documentation -->
 * <div class="ReleaseSpecificDocumentation">
 * <h3>HSQLDB-Specific Information:

 *
 * <b>JRE 1.1.x Notes: 

 *
 * In general, JDBC 2 support requires Java 1.2 and above, and JDBC3 requires
 * Java 1.4 and above. In HSQLDB, support for methods introduced in different
 * versions of JDBC depends on the JDK version used for compiling and building
 * HSQLDB.<p>
 *
 * Since 1.7.0, all JDBC 2 methods can be called while executing under the
 * version 1.1.x
 * <em>Java Runtime EnvironmentTM.
 * However, in addition to this technique requiring explicit casts to the
 * org.hsqldb.jdbcXXX classes, some of these method calls require
 * <code>int values that are defined only in the JDBC 2 or greater
 * version of the {@link java.sql.ResultSet ResultSet} interface.  For this
 * reason these values are defined in {@link jdbcResultSet jdbcResultSet}.<p>
 *
 * In a JRE 1.1.x environment, calling JDBC 2 methods that take or return the
 * JDBC2-only <code>ResultSet values can be achieved by referring
 * to them in parameter specifications and return value comparisons,
 * respectively, as follows: <p>
 *
 * <pre class="JavaCodeExample">
 * jdbcResultSet.FETCH_FORWARD
 * jdbcResultSet.TYPE_FORWARD_ONLY
 * jdbcResultSet.TYPE_SCROLL_INSENSITIVE
 * jdbcResultSet.CONCUR_READ_ONLY
 * //etc.
 * </pre> 

 *
 * However, please note that code written to use HSQLDB JDBC 2 features under
 * JDK 1.1.x will not be compatible for use with other JDBC 2 drivers. Please
 * also note that this feature is offered solely as a convenience to developers
 * who must work under JDK 1.1.x due to operating constraints, yet wish to
 * use some of the more advanced features available under the JDBC 2
 * specification. <p>
 *
 * (fredt@users)<br>
 * (boucherb@users)<p>
 *
 * </div>
 * <!-- end release-specific documentation -->
 *
 * @author boucherb@users
 * @author fredt@user
 * @version 1.8.0
 * @see jdbcConnection#createStatement
 * @see jdbcResultSet
 */
public class jdbcStatement implements Statement {

    /**
     * Whether this Statement has been explicitly closed.  A jdbcConnection
     * object now explicitly closes all of its open jdbcXXXStatement objects
     * when it is closed.
     */
    volatile boolean isClosed;

    /** Is escape processing enabled? */
    private boolean isEscapeProcessing = true;

    /** The connection used to execute this statement. */
    protected jdbcConnection connection;

    /** The maximum number of rows to generate when executing this statement. */
    protected int maxRows;

    /** The result of executing this statement. */
    protected Result resultIn;

    /** The result set type obtained by executing this statement. */
    protected int rsType = jdbcResultSet.TYPE_FORWARD_ONLY;

    /** Used by this statement to communicate non-batched requests. */
    protected Result resultOut = new Result(ResultConstants.SQLEXECDIRECT);

    /** Use by this statement to communicate batched execution requests */
    protected Result batchResultOut = null;

    // boucherb@users
    // NOTE:
    // This method is synchronized since resultIn is an instance attribute
    // and thus it is theoretically possible that a race condition occurs
    // in which a different thread executes fetchResult(sql), replacing
    // resultIn before it gets assigned propery to the new result set.
    // fredt - this class is not supposed to be called multi-threaded -
    // For example, if two threads call execute() then both call getResult() in
    // the wrong order, the ResultSet object for one call could actually belong
    // to the other call.

    /**
     * <!-- start generic documentation -->
     * Executes the given SQL statement, which returns a single
     * <code>ResultSet object. 

     * <!-- end generic documentation -->
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * This method should not be used for statements other than SELECT queries.<p>
     *
     * Including 1.7.2, HSQLDB does not throw an exception when the statement
     * is a DDL statement or an UPDATE or DELETE statement. This will certainly
     * change in future version.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param sql an SQL statement to be sent to the database, typically a
     *      static SQL <code>SELECT statement
     * @return a <code>ResultSet object that contains the data produced
     *       by the given query; never <code>null
     * @exception SQLException if a database access error occurs or the given
     *          SQL statement produces anything other than a single
     *          <code>ResultSet object
     */
    public ResultSet executeQuery(String sql) throws SQLException {

        checkClosed();
        connection.clearWarningsNoCheck();
        fetchResult(sql);

        return new jdbcResultSet(this, resultIn, connection.connProperties,
                                 connection.isNetConn);
    }

    /**
     * <!-- start generic documentation -->
     * Executes the given SQL statement, which may be an <code>INSERT,
     * <code>UPDATE, or DELETE statement or an
     * SQL statement that returns nothing, such as an SQL DDL statement. <p>
     * <!-- end generic documentation -->
     *
     * @param sql an SQL <code>INSERT, UPDATE or
     * <code>DELETE statement or an SQL statement that returns nothing
     * @return either the row count for <code>INSERT, UPDATE
     * or <code>DELETE statements, or 0 for SQL statements
     * that return nothing
     * @exception SQLException if a database access error occurs or the given
     *          SQL statement produces a <code>ResultSet object
     */
    public int executeUpdate(String sql) throws SQLException {

        checkClosed();
        connection.clearWarningsNoCheck();
        fetchResult(sql);

        if (resultIn == null || resultIn.isData()) {

            /**
             * @todo: - fredt@users - check for type of statement _must_ be done
             * in the engine and error returned _without_ executing
             */
            throw new SQLException(
                Trace.getMessage(Trace.jdbcStatement_executeUpdate));
        } else if (resultIn.isError()) {
            Util.throwError(resultIn);
        }

        return resultIn.getUpdateCount();
    }

    /**
     * <!-- start generic documentation -->
     * Releases this <code>Statement 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 on a Statement
     * object that is already closed has no effect.
     * <P>
     * <B>Note: A Statement object is automatically closed
     * when it is garbage collected. When a <code>Statement object is
     * closed, its current <code>ResultSet object, if one exists, is
     * also closed. <p>
     * <!-- end generic documentation -->
     *
     * @exception SQLException if a database access error occurs
     */
    public synchronized void close() throws SQLException {

        if (isClosed) {
            return;
        }

        batchResultOut = null;
        connection     = null;
        resultIn       = null;
        resultOut      = null;
        isClosed       = true;
    }

    //----------------------------------------------------------------------

    /**
     * <!-- start generic documentation -->
     * Retrieves the maximum number of bytes that can be
     * returned for character and binary column values in a <code>ResultSet
     * object produced by this <code>Statement object.
     * This limit applies only to <code>BINARY,
     * <code>VARBINARY, LONGVARBINARY, CHAR,
     * <code>VARCHAR, and LONGVARCHAR
     * columns.  If the limit is exceeded, the excess data is silently
     * discarded. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, HSQLDB always returns zero, meaning there
     * is no limit.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return the current column size limit for columns storing character and
     *       binary values; zero means there is no limit
     * @exception SQLException if a database access error occurs
     * @see #setMaxFieldSize
     */
    public int getMaxFieldSize() throws SQLException {

        checkClosed();

        return 0;
    }

    /**
     * <!-- start generic documentation -->
     * Sets the limit for the maximum number of bytes in a <code>ResultSet
     * column storing character or binary values to
     * the given number of bytes.  This limit applies
     * only to <code>BINARY, VARBINARY,
     * <code>LONGVARBINARY, CHAR, VARCHAR, and
     * <code>LONGVARCHAR fields.  If the limit is exceeded, the excess data
     * is silently discarded. For maximum portability, use values
     * greater than 256. <p>
     * <!-- emd generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, calls to this method are simply ignored; HSQLDB always
     * stores the full number of bytes when dealing with any of the field types
     * mentioned above. These types all have an absolute maximum element upper
     * bound determined by the Java array index limit
     * java.lang.Integer.MAX_VALUE.  For XXXBINARY types, this translates to
     * Integer.MAX_VALUE bytes.  For XXXCHAR types, this translates to
     * 2 * Integer.MAX_VALUE bytes (2 bytes / character)
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param max the new column size limit in bytes; zero means there is no limit
     * @exception SQLException if a database access error occurs
     *          or the condition max >= 0 is not satisfied
     * @see #getMaxFieldSize
     */
    public void setMaxFieldSize(int max) throws SQLException {

        checkClosed();

        if (max < 0) {
            throw Util.sqlException(Trace.INVALID_JDBC_ARGUMENT);
        }
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the maximum number of rows that a
     * <code>ResultSet object produced by this
     * <code>Statement object can contain.  If this limit is exceeded,
     * the excess rows are silently dropped. <p>
     * <!-- start generic documentation -->
     *
     * @return the current maximum number of rows for a <code>ResultSet
     *       object produced by this <code>Statement object;
     *       zero means there is no limit
     * @exception SQLException if a database access error occurs
     * @see #setMaxRows
     */
    public int getMaxRows() throws SQLException {

        checkClosed();

        return maxRows;
    }

    /**
     * <!-- start generic documentation -->
     * Sets the limit for the maximum number of rows that any
     * <code>ResultSet object can contain to the given number.
     * If the limit is exceeded, the excess
     * rows are silently dropped. <p>
     * <!-- end generic documentation -->
     *
     * @param max the new max rows limit; zero means there is no limit
     * @exception SQLException if a database access error occurs
     *          or the condition max >= 0 is not satisfied
     * @see #getMaxRows
     */
    public void setMaxRows(int max) throws SQLException {

        checkClosed();

        if (max < 0) {
            throw Util.sqlException(Trace.INVALID_JDBC_ARGUMENT);
        }

        maxRows = max;
    }

    /**
     * <!-- start generic documentation -->
     * 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.
     *
     * Note: Since prepared statements have usually been parsed prior
     * to making this call, disabling escape processing for
     * <code>PreparedStatements objects will have no effect. 

     * <!-- end generic documentation -->
     *
     * @param enable <code>true to enable escape processing;
     *     <code>false to disable it
     * @exception SQLException if a database access error occurs
     */
    public void setEscapeProcessing(boolean enable) throws SQLException {

        checkClosed();

        isEscapeProcessing = enable;
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the number of seconds the driver will
     * wait for a <code>Statement object to execute. If the
     * limit is exceeded, an <code>SQLException is thrown. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, HSQLDB always returns zero, meaning there
     * is no limit.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return the current query timeout limit in seconds; zero means there is
     *       no limit
     * @exception SQLException if a database access error occurs
     * @see #setQueryTimeout
     */
    public int getQueryTimeout() throws SQLException {

        checkClosed();

        return 0;
    }

    /**
     * <!-- start generic documentation -->
     * Sets the number of seconds the driver will wait for a
     * <code>Statement object to execute to the given number of seconds.
     * If the limit is exceeded, an <code>SQLException is thrown. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, calls to this method are ignored; HSQLDB waits an
     * unlimited amount of time for statement execution
     * requests to return.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param seconds the new query timeout limit in seconds; zero means
     *     there is no limit
     * @exception SQLException if a database access error occurs
     *         or the condition seconds >= 0 is not satisfied
     * @see #getQueryTimeout
     */
    public void setQueryTimeout(int seconds) throws SQLException {

        checkClosed();

        if (seconds < 0) {
            throw Util.sqlException(Trace.INVALID_JDBC_ARGUMENT);
        }
    }

    /**
     * <!-- start generic documentation -->
     * Cancels this <code>Statement 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. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, HSQLDB does <i>not support aborting a SQL
     * statement; calls to this method are ignored.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @exception SQLException if a database access error occurs
     */
    public void cancel() throws SQLException {
        checkClosed();
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the first warning reported by calls on this <code>Statement object.
     * Subsequent <code>Statement object warnings will be chained to this
     * <code>SQLWarning object.
     *
     * <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 object; doing so will cause an SQLException
     * to be thrown.
     *
     * <P>Note: If you are processing a ResultSet object, any
     * warnings associated with reads on that <code>ResultSet object
     * will be chained on it rather than on the <code>Statement
     * object that produced it. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, HSQLDB never produces Statement warnings;
     * this method always returns null.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return the first <code>SQLWarning object or null
     *       if there are no warnings
     * @exception SQLException if a database access error occurs or this
     *          method is called on a closed statement
     */
    public SQLWarning getWarnings() throws SQLException {

        checkClosed();

        return null;
    }

    /**
     * <!-- start generic documentation -->
     * Clears all the warnings reported on this <code>Statement
     * object. After a call to this method,
     * the method <code>getWarnings will return
     * <code>null until a new warning is reported for this
     * <code>Statement object. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including HSQLDB 1.7.2, <code>SQLWarning objects are
     * never produced for Statement Objects; calls to this method are
     * ignored.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @exception SQLException if a database access error occurs
     */
    public void clearWarnings() throws SQLException {
        checkClosed();
    }

    /**
     * <!-- start generic documentation -->
     * Sets the SQL cursor name to the given <code>String, which
     * will be used by subsequent <code>Statement object
     * <code>execute methods. This name can then be
     * used in SQL positioned update or delete statements to identify the
     * current row in the <code>ResultSet 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 statement
     * should have the form <code>SELECT FOR UPDATE.  If
     * <code>FOR UPDATE is not present, positioned updates may fail.
     *
     * <P>Note: By definition, the execution of positioned updates and
     * deletes must be done by a different <code>Statement object than
     * the one that generated the <code>ResultSet object being used for
     * positioning. Also, cursor names must be unique within a connection. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, HSQLDB does not support named cursors,
     * updateable results or table locking via <code>SELECT FOR UPDATE;
     * calls to this method are ignored.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param name the new cursor name, which must be unique within
     *           a connection
     * @exception SQLException if a database access error occurs
     */
    public void setCursorName(String name) throws SQLException {
        checkClosed();
    }

    //----------------------- Multiple Results --------------------------

    /**
     * <!-- start generic documentation -->
     * Executes the given SQL statement, which may return multiple results.
     * 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 method executes an SQL statement and indicates the
     * form of the first result.  You must then use the methods
     * <code>getResultSet or getUpdateCount
     * to retrieve the result, and <code>getMoreResults to
     * move to any subsequent result(s). <p>
     * <!-- end generic documentation -->
     *
     * @param sql any SQL statement
     * @return <code>true if the first result is a ResultSet
     *       object; <code>false if it is an update count or there are
     *       no results
     * @exception SQLException if a database access error occurs
     * @see #getResultSet
     * @see #getUpdateCount
     * @see #getMoreResults
     */
    public boolean execute(String sql) throws SQLException {

        checkClosed();
        connection.clearWarningsNoCheck();
        fetchResult(sql);

        return resultIn.isData();
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the current result as a <code>ResultSet object.
     * This method should be called only once per result. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Without an interceding call to executeXXX, each invocation of this
     * method will produce a new, initialized ResultSet instance referring to
     * the current result, if any.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return the current result as a <code>ResultSet object or
     *      <code>null if the result is an update count or there
     *      are no more results
     * @exception SQLException if a database access error occurs
     * @see #execute
     */
    public ResultSet getResultSet() throws SQLException {

        checkClosed();

        return resultIn == null || !resultIn.isData() ? null
                                                      : new jdbcResultSet(this,
                                                      resultIn,
                                                          connection.connProperties,
                                                              connection.isNetConn);
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the current result as an update count;
     * if the result is a <code>ResultSet object or there are no more results, -1
     * is returned. This method should be called only once per result. <p>
     * <!-- end generic documentation -->
     *
     * @return the current result as an update count; -1 if the current result is a
     * <code>ResultSet object or there are no more results
     * @exception SQLException if a database access error occurs
     * @see #execute
     */
    public int getUpdateCount() throws SQLException {

// fredt - omit checkClosed() in order to be able to handle the result of a
// SHUTDOWN query
//        checkClosed();
        return (resultIn == null || resultIn.isData()) ? -1
                                                       : resultIn
                                                       .getUpdateCount();
    }

    /**
     * <!-- start generic documentation -->
     * Moves to this <code>Statement object's next result, returns
     * <code>true if it is a ResultSet object, and
     * implicitly closes any current <code>ResultSet
     * object(s) obtained with the method <code>getResultSet.
     *
     * <P>There are no more results when the following is true:
     * <PRE>
     *    <code>(!getMoreResults() && (getUpdateCount() == -1)
     * </PRE> 

     * <!-- end generic documentation -->
     *
     * @return <code>true if the next result is a ResultSet
     *       object; <code>false if it is an update count or there are
     *       no more results
     * @exception SQLException if a database access error occurs
     * @see #execute
     */
    public boolean getMoreResults() throws SQLException {

        checkClosed();

        resultIn = null;

        return false;
    }

    //--------------------------JDBC 2.0-----------------------------

    /**
     * <!-- start generic documentation -->
     * Gives the driver a hint as to the direction in which
     * rows will be processed in <code>ResultSet
     * objects created using this <code>Statement object.  The
     * default value is <code>ResultSet.FETCH_FORWARD.
     * <P>
     * Note that this method sets the default fetch direction for
     * result sets generated by this <code>Statement object.
     * Each result set has its own methods for getting and setting
     * its own fetch direction. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, HSQLDB supports only <code>FETCH_FORWARD. 

     *
     * Setting any other value will throw an <code>SQLException
     * stating that the operation is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param direction the initial direction for processing rows
     * @exception SQLException if a database access error occurs
     * or the given direction
     * is not one of <code>ResultSet.FETCH_FORWARD,
     * <code>ResultSet.FETCH_REVERSE, or
     * <code>ResultSet.FETCH_UNKNOWN 

     *
     * HSQLDB throws for all values except <code>FETCH_FORWARD
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *    for jdbcStatement)
     * @see #getFetchDirection
     */
    public void setFetchDirection(int direction) throws SQLException {

        checkClosed();

        if (direction != jdbcResultSet.FETCH_FORWARD) {
            throw Util.notSupported();
        }
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the direction for fetching rows from
     * database tables that is the default for result sets
     * generated from this <code>Statement object.
     * If this <code>Statement object has not set
     * a fetch direction by calling the method <code>setFetchDirection,
     * the return value is implementation-specific. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, HSQLDB always returns FETCH_FORWARD.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return the default fetch direction for result sets generated
     *        from this <code>Statement object
     * @exception SQLException if a database access error occurs
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *    for jdbcStatement)
     * @see #setFetchDirection
     */
    public int getFetchDirection() throws SQLException {

        checkClosed();

        return jdbcResultSet.FETCH_FORWARD;
    }

    /**
     * <!-- start generic documentation -->
     * Gives the JDBC driver a hint as to the number of rows that should
     * be fetched from the database when more rows are needed.  The number
     * of rows specified affects only result sets created using this
     * statement. If the value specified is zero, then the hint is ignored.
     * The default value is zero. <p>
     * <!-- start generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, calls to this method are ignored;
     * HSQLDB fetches each result completely as part of
     * executing its statement.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param rows the number of rows to fetch
     * @exception SQLException if a database access error occurs, or the
     *     condition 0 <=  <= this.getMaxRows()
     *     is not satisfied. <p>
     *
     *     HSQLDB never throws an exception, since calls to this method
     *     are always ignored.
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *   for jdbcStatement)
     * @see #getFetchSize
     */
    public void setFetchSize(int rows) throws SQLException {
        checkClosed();
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the number of result set rows that is the default
     * fetch size for <code>ResultSet objects
     * generated from this <code>Statement object.
     * If this <code>Statement object has not set
     * a fetch size by calling the method <code>setFetchSize,
     * the return value is implementation-specific. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <b>HSQLDB-Specific Information 

     *
     * Including 1.7.2, this method always returns 0.
     * HSQLDB fetches each result completely as part of
     * executing its statement
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return the default fetch size for result sets generated
     *      from this <code>Statement object
     * @exception SQLException if a database access error occurs
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *  for jdbcStatement)
     * @see #setFetchSize
     */
    public int getFetchSize() throws SQLException {

        checkClosed();

        return 0;
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the result set concurrency for <code>ResultSet objects
     * generated by this <code>Statement object. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Including 1.7.2, HSQLDB supports only
     * <code>CONCUR_READ_ONLY concurrency.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return either <code>ResultSet.CONCUR_READ_ONLY or
     * <code>ResultSet.CONCUR_UPDATABLE (not supported)
     * @exception SQLException if a database access error occurs
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *  for jdbcStatement)
     */
    public int getResultSetConcurrency() throws SQLException {

        checkClosed();

        return jdbcResultSet.CONCUR_READ_ONLY;
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the result set type for <code>ResultSet objects
     * generated by this <code>Statement object. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.0 and later versions support <code>TYPE_FORWARD_ONLY
     * and <code>TYPE_SCROLL_INSENSITIVE.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return one of <code>ResultSet.TYPE_FORWARD_ONLY,
     * <code>ResultSet.TYPE_SCROLL_INSENSITIVE, or
     * <code>ResultSet.TYPE_SCROLL_SENSITIVE (not supported) 

     *
     * <b>Note: Up to and including 1.7.1, HSQLDB never returns
     * <code>TYPE_SCROLL_SENSITIVE
     * @exception SQLException if a database access error occurs
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *   for jdbcStatement)
     */
    public int getResultSetType() throws SQLException {

// fredt - omit checkClosed() in order to be able to handle the result of a
// SHUTDOWN query
//        checkClosed();
        return rsType;
    }

    /**
     * <!-- start generic documentation -->
     * Adds the given SQL command to the current list of commmands for this
     * <code>Statement object. The commands in this list can be
     * executed as a batch by calling the method <code>executeBatch.
     * <P>
     * <B>NOTE:  This method is optional. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Starting with 1.7.2, this feature is supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param sql typically this is a static SQL <code>INSERT or
     * <code>UPDATE statement
     * @exception SQLException if a database access error occurs, or the
     * driver does not support batch updates
     * @see #executeBatch
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *   for jdbcStatement)
     */
    public void addBatch(String sql) throws SQLException {

        checkClosed();

        if (isEscapeProcessing) {
            sql = connection.nativeSQL(sql);
        }

        if (batchResultOut == null) {
            batchResultOut = new Result(ResultConstants.BATCHEXECDIRECT,
                                        new int[]{ Types.VARCHAR }, 0);
        }

        batchResultOut.add(new Object[]{ sql });
    }

    /**
     * <!-- start generic documentation -->
     * Empties this <code>Statement object's current list of
     * SQL commands.
     * <P>
     * <B>NOTE:  This method is optional. 

     * <!-- start generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Starting with HSQLDB 1.7.2, this feature is supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @exception SQLException if a database access error occurs or the
     * driver does not support batch updates
     * @see #addBatch
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *   for jdbcStatement)
     */
    public void clearBatch() throws SQLException {

        checkClosed();

        if (batchResultOut != null) {
            batchResultOut.clear();
        }
    }

    /**
     * <!-- start generic documentation -->
     * 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 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
     * 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 SUCCESS_NO_INFO -- 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, 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
     * 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 EXECUTE_FAILED -- indicates that the command failed
     * to execute successfully and occurs only if a driver continues to
     * process commands after a command fails
     * </OL>
     * <P>
     * A driver is not required to implement this method.
     * 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 obejct has been thrown. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Starting with HSQLDB 1.7.2, this feature is supported. <p>
     *
     * HSQLDB stops execution of commands in a batch when one of the commands
     * results in an exception. The size of the returned array equals the
     * number of commands that were executed successfully.<p>
     *
     * When the product is built under the JAVA1 target, an exception
     * is never thrown and it is the responsibility of the client software to
     * check the size of the  returned update count array to determine if any
     * batch items failed.  To build and run under the JAVA2 target, JDK/JRE
     * 1.3 or higher must be used.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @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.
     * @exception SQLException if a database access error occurs or the
     * driver does not support batch statements. Throws
     * {@link java.sql.BatchUpdateException}
     * (a subclass of <code>java.sql.SQLException) if one of the commands
     * sent  to the database fails to execute properly or attempts to return a
     * result set.
     * @since JDK 1.3 (JDK 1.1.x developers: read the new overview
     *   for jdbcStatement)
     */
    public int[] executeBatch() throws SQLException {

        int[]         updateCounts;
        int           batchCount;
        HsqlException he;

        checkClosed();
        connection.clearWarningsNoCheck();

        if (batchResultOut == null) {
            batchResultOut = new Result(ResultConstants.BATCHEXECDIRECT,
                                        new int[]{ Types.VARCHAR }, 0);
        }

        batchCount = batchResultOut.getSize();

        try {
            resultIn = connection.sessionProxy.execute(batchResultOut);
        } catch (HsqlException e) {
            batchResultOut.clear();

            throw Util.sqlException(e);
        }

        batchResultOut.clear();

        if (resultIn.isError()) {
            Util.throwError(resultIn);
        }

        updateCounts = resultIn.getUpdateCounts();

//#ifdef JAVA2FULL
        if (updateCounts.length != batchCount) {
            throw new BatchUpdateException("failed batch", updateCounts);
        }

//#else
/*
        if (updateCounts.length != batchCount) {
            throw new SQLException("failed batch, update count: "
                                   + updateCounts, "");
        }
*/

//#endif JAVA2
        return updateCounts;
    }

    /**
     * <!-- start generic documentation -->
     * Retrieves the <code>Connection object
     * that produced this <code>Statement object. 

     * <!-- end generic documentation -->
     *
     * @return the connection that produced this statement
     * @exception SQLException if a database access error occurs
     * @since JDK 1.2 (JDK 1.1.x developers: read the new overview
     *    for jdbcStatement)
     */
    public Connection getConnection() throws SQLException {

        checkClosed();

        return connection;
    }

    //--------------------------JDBC 3.0-----------------------------

    /**
     * <!-- start generic documentation -->
     * Moves to this <code>Statement object's next result, deals with
     * any current <code>ResultSet object(s) according  to the instructions
     * specified by the given flag, and returns
     * <code>true if the next result is a ResultSet object.
     *
     * <P>There are no more results when the following is true:
     * <PRE>
     *   <code>(!getMoreResults() && (getUpdateCount() == -1)
     * </PRE> 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException,
     * stating that the function is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param current one of the following <code>Statement
     *     constants indicating what should happen to current
     *     <code>ResultSet objects obtained using the method
     *     <code>getResultSet,
     *     <code>KEEP_CURRENT_RESULT, or
     *     <code>CLOSE_ALL_RESULTS
     * @return <code>true if the next result is a ResultSet
     *      object; <code>false if it is an update count or there are no
     *      more results
     * @exception SQLException if a database access error occurs
     * @since JDK 1.4, HSQLDB 1.7
     * @see #execute
     */
//#ifdef JAVA4
    public boolean getMoreResults(int current) throws SQLException {
        throw Util.notSupported();
    }

//#endif JAVA4

    /**
     * <!-- start generic documentation -->
     * Retrieves any auto-generated keys created as a result of executing this
     * <code>Statement object. If this Statement object did
     * not generate any keys, an empty <code>ResultSet
     * object is returned. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException,
     * stating that the function is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return a <code>ResultSet object containing the auto-generated key(s)
     *     generated by the execution of this <code>Statement object
     * @exception SQLException if a database access error occurs
     * @since JDK 1.4, HSQLDB 1.7
     */
//#ifdef JAVA4
    public ResultSet getGeneratedKeys() throws SQLException {
        throw Util.notSupported();
    }

//#endif JAVA4

    /**
     * <!-- start generic documentation -->
     * Executes the given SQL statement and signals the driver with the
     * given flag about whether the
     * auto-generated keys produced by this <code>Statement object
     * should be made available for retrieval. <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException,
     * stating that the function is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param sql must be an SQL <code>INSERT, UPDATE or
     *    <code>DELETE statement or an SQL statement that
     *    returns nothing
     * @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>Statement.NO_GENERATED_KEYS
     * @return either the row count for <code>INSERT, UPDATE
     *     or <code>DELETE statements, or 0 for SQL
     *     statements that return nothing
     * @exception SQLException if a database access error occurs, the given
     *        SQL statement returns a <code>ResultSet object, or
     *        the given constant is not one of those allowed
     * @since JDK 1.4, HSQLDB 1.7
     */
//#ifdef JAVA4
    public int executeUpdate(String sql,
                             int autoGeneratedKeys) throws SQLException {
        throw Util.notSupported();
    }

//#endif JAVA4

    /**
     * <!-- start generic documentation -->
     * 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.  The driver will ignore the array if the SQL statement
     * is not an <code>INSERT statement. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException,
     * stating that the function is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param sql an SQL <code>INSERT, UPDATE or
     *    <code>DELETE statement or an SQL statement that returns nothing,
     *    such as an SQL DDL statement
     * @param columnIndexes an array of column indexes indicating the columns
     *    that should be returned from the inserted row
     * @return either the row count for <code>INSERT, UPDATE,
     *     or <code>DELETE statements, or 0 for SQL statements
     *     that return nothing
     * @exception SQLException if a database access error occurs or the SQL
     *        statement returns a <code>ResultSet object
     * @since JDK 1.4, HSQLDB 1.7
     */
//#ifdef JAVA4
    public int executeUpdate(String sql,
                             int[] columnIndexes) throws SQLException {
        throw Util.notSupported();
    }

//#endif JAVA4

    /**
     * <!-- start generic documentation -->
     * 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.  The driver will ignore the array if the SQL statement
     * is not an <code>INSERT statement. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException,
     * stating that the function is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param sql an SQL <code>INSERT, UPDATE or
     *    <code>DELETE statement or an SQL statement that returns nothing
     * @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, UPDATE,
     *     or <code>DELETE statements, or 0 for SQL statements
     *     that return nothing
     * @exception SQLException if a database access error occurs
     * @since JDK 1.4, HSQLDB 1.7
     */
//#ifdef JAVA4
    public int executeUpdate(String sql,
                             String[] columnNames) throws SQLException {
        throw Util.notSupported();
    }

//#endif JAVA4

    /**
     * <!-- start generic documentation -->
     * 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 statement.
     * <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 method executes an SQL statement and indicates the
     * form of the first result.  You must then use the methods
     * <code>getResultSet or getUpdateCount
     * to retrieve the result, and <code>getMoreResults to
     * move to any subsequent result(s). <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException,
     * stating that the function is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @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; one of the following constants:
     *    <code>Statement.RETURN_GENERATED_KEYS or
     *      <code>Statement.NO_GENERATED_KEYS
     * @return <code>true if the first result is a ResultSet
     *     object; <code>false if it is an update count or there are
     *     no results
     * @exception SQLException if a database access error occurs
     * @see #getResultSet
     * @see #getUpdateCount
     * @see #getMoreResults
     * @see #getGeneratedKeys
     * @since JDK 1.4, HSQLDB 1.7
     */
//#ifdef JAVA4
    public boolean execute(String sql,
                           int autoGeneratedKeys) throws SQLException {
        throw Util.notSupported();
    }

//#endif JAVA4

    /**
     * <!-- start generic documentation -->
     * 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 given SQL statement
     * is not an <code>INSERT statement.
     * <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 method executes an SQL statement and indicates the
     * form of the first result.  You must then use the methods
     * <code>getResultSet or getUpdateCount
     * to retrieve the result, and <code>getMoreResults to
     * move to any subsequent result(s). <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException,
     * stating that the function is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @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
     * @return <code>true if the first result is a ResultSet
     *     object; <code>false if it is an update count or there
     *     are no results
     * @exception SQLException if a database access error occurs
     * @see #getResultSet
     * @see #getUpdateCount
     * @see #getMoreResults
     * @since JDK 1.4, HSQLDB 1.7
     */
//#ifdef JAVA4
    public boolean execute(String sql,
                           int[] columnIndexes) throws SQLException {
        throw Util.notSupported();
    }

//#endif JAVA4

    /**
     * <!-- start generic documentation -->
     * 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 given SQL statement
     * is not an <code>INSERT statement.
     * <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 method executes an SQL statement and indicates the
     * form of the first result.  You must then use the methods
     * <code>getResultSet or getUpdateCount
     * to retrieve the result, and <code>getMoreResults to
     * move to any subsequent result(s). <p>
     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * HSQLDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException,
     * stating that the function is not supported.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @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
     * @return <code>true if the next result is a ResultSet
     *     object; <code>false if it is an update count or there
     *     are no more results
     * @exception SQLException if a database access error occurs
     * @see #getResultSet
     * @see #getUpdateCount
     * @see #getMoreResults
     * @see #getGeneratedKeys
     * @since JDK 1.4, HSQLDB 1.7
     */
//#ifdef JAVA4
    public boolean execute(String sql,
                           String[] columnNames) throws SQLException {
        throw Util.notSupported();
    }

//#endif JAVA4

    /**
     * <!-- start generic documentation -->
     * Retrieves the result set holdability for <code>ResultSet objects
     * generated by this <code>Statement object. 

     * <!-- end generic documentation -->
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information: 

     *
     * Starting with 1.7.2, this method returns HOLD_CURSORS_OVER_COMMIT
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @return either <code>ResultSet.HOLD_CURSORS_OVER_COMMIT or
     *      <code>ResultSet.CLOSE_CURSORS_AT_COMMIT
     * @exception SQLException if a database access error occurs
     * @since JDK 1.4, HSQLDB 1.7
     */
//#ifdef JAVA4
    public int getResultSetHoldability() throws SQLException {
        return jdbcResultSet.HOLD_CURSORS_OVER_COMMIT;
    }

//#endif JAVA4
    // -------------------- Internal Implementation ----------------------------

    /**
     * Constructs a new jdbcStatement with the specified connection and
     * result type.
     *
     * @param  c the connection on which this statement will execute
     * @param  type the kind of results this will return
     */
    jdbcStatement(jdbcConnection c, int type) {

        // PRE: assume connection is not null and is not closed
        // PRE: assume type is a valid result set type code
        connection = c;
        rsType     = type;
    }

    /**
     * Retrieves whether this statement is closed.
     */
    synchronized public boolean isClosed() {
        return isClosed;
    }

    /**
     * An internal check for closed statements.
     *
     * @throws SQLException when the connection is closed
     */
    void checkClosed() throws SQLException {

        if (isClosed) {
            throw Util.sqlException(Trace.STATEMENT_IS_CLOSED);
        }

        if (connection.isClosed) {
            throw Util.sqlException(Trace.CONNECTION_IS_CLOSED);
        }
    }

    /**
     * Internal result producer for jdbcStatement (sqlExecDirect mode). <p>
     *
     * @param sql a character sequence representing the SQL to be executed
     * @throws SQLException when a database access error occurs
     */
    private void fetchResult(String sql) throws SQLException {

        if (isEscapeProcessing) {
            sql = connection.nativeSQL(sql);
        }

        resultIn = null;

        resultOut.setMainString(sql);
        resultOut.setMaxRows(maxRows);

        try {
            resultIn = connection.sessionProxy.execute(resultOut);

            if (resultIn.isError()) {
                throw new HsqlException(resultIn);
            }
        } catch (HsqlException e) {
            throw Util.sqlException(e);
        }
    }
//#ifdef JAVA6
/*
    public void setPoolable(boolean poolable) throws SQLException
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    public boolean isPoolable() throws SQLException
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    public <T> T unwrap(Class iface) throws SQLException
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    public boolean isWrapperFor(Class<?> iface) throws SQLException
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }
*/
//#endif JAVA6
}