embedresultset.java

derby database source code.good for you.

			}

		    boolean onRow = (currentRow!=null);

			//if (onRow && !(currentRow instanceof org.apache.derby.impl.sql.execute.ValueRow))
			//	System.out.println(currentRow.getClass());

		    /*
			    Connection.setAutoCommit says that a statement completes,
			    and will autoCommit, when it fetches the last row or is closed.
			    This means a close will get a "Cursor already closed" error.
				This rule only applies when doing a next() - if it were applied
				to scrolling actions (like FIRST or LAST) it would close
				the cursor when doing any operation on a scrolling cursor.

			    if autocommit, this will commit
		     */
		    if (!onRow && (position == NEXT)) {

		     // In case of resultset for MetaData, we will only commit
		     // if we are the only statement currently opened for this
		     // connection; otherwise we don't want to affect other
		     // resultSet's by committing the MetaData one.
		     // There is no internal xact (xact isolation) for MetaData type
		     // of resultSet; therefore committing (to release locks) would end
		     // up committing all the other resultSet for this connection.
		     //
		     // We do synchronize on the connection, therefore Activation count
		     // should be valid and protected.
		     //
			//LanguageConnectionContext lcc = getEmbedConnection().getLanguageConnection();
		     if (forMetaData && (lcc.getActivationCount() > 1)) {
		     	// we do not want to commit here as there seems to be other
		     	// statements/resultSets currently opened for this connection.
		     } else if (owningStmt != null)
				 // allow the satement to commit if required.
		     	owningStmt.resultSetClosing(this);
		    }

			rowData = onRow ? currentRow.getRowArray() : null;

			return onRow;
			} finally {
			    restoreContextStack();
			}
		}

	}




    /**
     * In some cases, it is desirable to immediately release a
     * ResultSet's database and JDBC resources instead of waiting for
     * this to happen when it is automatically closed; the close
     * method provides this immediate release.
     *
     * <P><B>Note:</B> A ResultSet is automatically closed by the
     * Statement that generated it when that Statement is closed,
     * re-executed, or is used to retrieve the next result from a
     * sequence of multiple results. A ResultSet is also automatically
     * closed when it is garbage collected.
	 * @exception SQLException thrown on failure.
     */
    public void close() throws SQLException	{

		/* if this result is already closed, don't try to close again
		 * we may have closed it earlier because of an error and trying
		 * to close again will cause a different problem if the connection
		 * has been closed as in XA error handling
		 */
		if (isClosed)
			return;

		closeCurrentStream();	// closing currentStream does not depend on the
								// underlying connection.  Do this outside of
								// the connection synchronization.
		// Would like to throw an exception if already closed, but
		// some code assumes you can close a ResultSet more than once.
		// checkIfClosed("close");

		// synchronize out here so the close and the autocommit are
		// both in the same sync block.
		synchronized (getConnectionSynchronization()) {

			try {
				setupContextStack(); // make sure there's context
			} catch (SQLException se) {
				// we may get an exception here if this is part of an XA transaction
				// and the transaction has been committed
				// just give up and return
				return;
			}

			try	{
				try	{
				    theResults.finish(); // release the result set, don't just close it
				} catch (Throwable t) {
					throw handleException(t);
				}

			    // In case of resultset for MetaData, we will only commit
		        // if we are the only statement currently opened for this
		        // connection; otherwise we don't want to affect other
		        // resultSet's by committing the MetaData one.
		        // There is no internal xact (xact isolation) for MetaData type
		        // of resultSet; therefore committing (to release locks) would end
		        // up committing all the other resultSet for this connection.
		        //
		        // We do synchronize on the connection, therefore Activation count
		        // should be valid and protected.
		        //
		        if (forMetaData) {

					LanguageConnectionContext lcc = getEmbedConnection().getLanguageConnection();
		        	if (lcc.getActivationCount() > 1) {
		     		  // we do not want to commit here as there seems to be other
					  // statements/resultSets currently opened for this connection.
					} else if (owningStmt != null)
						// allow the satement to commit if required.
		     			owningStmt.resultSetClosing(this);
		
				} else if (owningStmt != null) {
						// allow the satement to commit if required.
		     			owningStmt.resultSetClosing(this);
		     	}

			} finally {
				isClosed = true;
			    restoreContextStack();
			}

			// the idea is to release resources, so:
			currentRow = null;
			rowData = null;
			rMetaData = null; // let it go, we can make a new one
	    //since we are moving off of the current row(by closing the resultset), need to initialize state corresponding to updateRow implementation
	    for (int i=0; i < columnGotUpdated.length; i++)
				columnGotUpdated[i] = false;
	    currentRowHasBeenUpdated = false;

			// we hang on to theResults and messenger
			// in case more calls come in on this resultSet
		}

	}

    /**
     * A column may have the value of SQL NULL; wasNull reports whether
     * the last column read had this special value.
     * Note that you must first call getXXX on a column to try to read
     * its value and then call wasNull() to find if the value was
     * the SQL NULL.
     *
     * <p> we take the least exception approach and simply return false
     * if no column has been read yet.
     *
     * @return true if last column read was SQL NULL
	 *
	 * @exception SQLException		Thrown if this ResultSet is closed
     */
    public final boolean wasNull() throws SQLException {
		checkIfClosed("wasNull");
		return wasNull;
	}

    //======================================================================
    // Methods for accessing results by column index
    //======================================================================

    /**
     * Get the value of a column in the current row as a Java String.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is null
	 * @exception SQLException thrown on failure.
     */
    public final String getString(int columnIndex) throws SQLException {

			try {

				DataValueDescriptor dvd = getColumn(columnIndex);

				if (wasNull = dvd.isNull())
					return null;

				String value = dvd.getString();

				// check for the max field size limit 
                if (maxFieldSize > 0 && isMaxFieldSizeType(getColumnType(columnIndex)))
                {
                    if (value.length() > maxFieldSize )
                    {
                        value = value.substring(0, maxFieldSize);
                    }
                }
     
				return value;

			} catch (Throwable t) {
				throw noStateChangeException(t);
			}
	}

    /**
     * Get the value of a column in the current row as a Java boolean.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is false
	 * @exception SQLException thrown on failure.
     */
    public final boolean getBoolean(int columnIndex) throws SQLException {


		try {

			DataValueDescriptor dvd = getColumn(columnIndex);

			if (wasNull = dvd.isNull())
				return false;

			return dvd.getBoolean();

		} catch (StandardException t) {
			throw noStateChangeException(t);
		}
	}

    /**
     * Get the value of a column in the current row as a Java byte.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is 0
	 * @exception SQLException thrown on failure.
     */
    public final byte getByte(int columnIndex) throws SQLException {

		try {

			DataValueDescriptor dvd = getColumn(columnIndex);

			if (wasNull = dvd.isNull())
				return 0;

			return dvd.getByte();

		} catch (StandardException t) {
			throw noStateChangeException(t);
		}
	}

    /**
     * Get the value of a column in the current row as a Java short.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is 0
	 * @exception SQLException thrown on failure.
     */
    public final short getShort(int columnIndex) throws SQLException {


		try {

			DataValueDescriptor dvd = getColumn(columnIndex);

			if (wasNull = dvd.isNull())
				return 0;

			return dvd.getShort();

		} catch (StandardException t) {
			throw noStateChangeException(t);
		}
	}

    /**
     * Get the value of a column in the current row as a Java int.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is 0
	 * @exception SQLException thrown on failure.
     */
    public final int getInt(int columnIndex) throws SQLException	{

		try {

			DataValueDescriptor dvd = getColumn(columnIndex);

			if (wasNull = dvd.isNull())
				return 0;

			return dvd.getInt();

		} catch (StandardException t) {
			throw noStateChangeException(t);
		}
	}

    /**
     * Get the value of a column in the current row as a Java long.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is 0
	 * @exception SQLException thrown on failure.
     */
    public final long getLong(int columnIndex) throws SQLException {

		try {

			DataValueDescriptor dvd = getColumn(columnIndex);

			if (wasNull = dvd.isNull())
				return 0;

			return dvd.getLong();

		} catch (StandardException t)	{
			throw noStateChangeException(t);
		}
	}

    /**
     * Get the value of a column in the current row as a Java float.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is 0
	 * @exception SQLException thrown on failure.
     */
    public final float getFloat(int columnIndex) throws SQLException {

		try {

			DataValueDescriptor dvd = getColumn(columnIndex);

			if (wasNull = dvd.isNull())
				return 0.0F;

			return dvd.getFloat();

		} catch (StandardException t)	{
			throw noStateChangeException(t);
		}
	}

    /**
     * Get the value of a column in the current row as a Java double.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is 0
	 * @exception SQLException thrown on failure.
     */
    public final double getDouble(int columnIndex) throws SQLException {

		try {

			DataValueDescriptor dvd = getColumn(columnIndex);

			if (wasNull = dvd.isNull())
				return 0.0;

			return dvd.getDouble();

		} catch (StandardException t)	{
			throw noStateChangeException(t);
		}
	}

    /**
     * Get the value of a column in the current row as a Java byte array.
     * The bytes represent the raw values returned by the driver.
     *
     * @param columnIndex the first column is 1, the second is 2, ...
     * @return the column value; if the value is SQL NULL, the result is null
	 * @exception SQLException thrown on failure.
     */
    public final byte[] getBytes(int columnIndex) throws SQLException	{

		try {

			DataValueDescriptor dvd = getColumn(columnIndex);

			if (wasNull = dvd.isNull())
				return null;

			byte[] value = dvd.getBytes();

            // check for the max field size limit 
            if (maxFieldSize > 0 && isMaxFieldSizeType(getColumnType(columnIndex)))
            {
                 if (value.length > maxFieldSize)
                 {
                     byte [] limited_value = new byte[maxFieldSize];
                     System.arraycopy(value, 0, limited_value, 
                                                   0 , maxFieldSize);
                     value = limited_value;
                 }
             }
			
			return value;

		} catch (StandardException t) {
			throw noStateChangeException(t);
		}
	}

    /**
     * Get the value of a column in the current row as a java.sql.Date object.
     *