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/PreparedQuery.java
groupName = binding.getAggregatOns( ).get( 0 ).toString( );
					}
					
					if ( ( !groupName
							.equals( IBaseExpression.GROUP_OVERALL ) )
							&& !groupNameSet.contains( groupName ) )
					{
						throw new DataException( ResourceConstants.GROUP_NOT_EXIST,
								new Object[]{
								groupName, key
								} );
					}
				}
			}
			mappingParentColumnBinding( );
			
			for ( int i = 0; i <= groups.size( ); i++ )
			{
				prepareGroup( baseQueryDefn, i, cx );
			}
		}
		finally
		{			
		    Context.exit();
		}
	}
	
	/**
	 * @throws DataException 
	 *