Bug 118592 Report error
please see attached design file.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/ResultIterator.java
* @return The value of the given expression as a Boolean. It could be null.
	 * @throws DataException
	 *             if error occurs in Data Engine
	 */
	public Boolean getBoolean( IBaseExpression dataExpr ) throws DataException
	{
		try
		{
			return DataTypeUtil.toBoolean( getValue( dataExpr ) );
		}
		catch ( BirtException e )
		{
			DataException e1 = new DataException( ResourceConstants.DATATYPEUTIL_ERROR,
					e );
			logger.logp( Level.FINE,
					ResultIterator.class.getName( ),
					"getBoolean",
					"An error is thrown by DataTypeUtil.",
					e1 );
			throw e1;
		}
	}
	/**
	 * Returns the value of a query result expression as an Integer, by type
	 * casting the Object returned by getValue. <br>
	 * A convenience method for the API consumer. <br>
	 * If the expression value has an incompatible type, a ClassCastException is
	 * thrown at runtime.
	 * 
	 * @param dataExpr