Bug 195970 Two issues when evaluate a query inlcuding a subquery[07]
Description: Currently, when evaluating a query which includes a subquery, the query will be evaluated twice. The binding of query will pass to subquery twice. If user write a java script such as new Date() and i++. The result of query will be incorrect. Another issue: when write the report document, the binding of query will be written twice and the performance is not good to evalulate it twice.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedSubquery.java
* @return
	 * @throws DataException
	 */
	QueryResults execute( IResultIterator parentIterator, Scriptable scope ) 
		throws DataException
	{
		logger.logp( Level.FINER,
				PreparedSubquery.class.getName( ),
				"execute",
				"start to execute a PreparedSubquery." );
		try
		{
			return preparedQuery.doPrepare( null,
					scope,
					new SubQueryExecutor( parentIterator ),
					getDataSourceQuery( ) );
		}
		finally
		{
			logger.logp( Level.FINER,
					PreparedSubquery.class.getName( ),
					"execute",
					"finish executing a PreparedSubquery." );
		}
	}
	
	/**
	 * Concrete class of PreparedQuery.Executor used in PreparedSubquery
	 */
	private class SubQueryExecutor extends QueryExecutor