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
parentResultClass.getFieldName( i + 1 ),
						parentResultClass.getFieldName( i + 1 ),
						parentResultClass.getFieldValueClass( i + 1 ),
						parentResultClass.getFieldNativeTypeName( i + 1 ),
						parentResultClass.isCustomField( i + 1 ) );
				columnsList.add( columnMetaData );
				columnMetaData.setAlias( parentResultClass.getFieldAlias( i + 1 ) );
			}
			
			int count = columnsList.size( );
			Iterator it = computedColumns.iterator( );
			for ( int j = columnsList.size( ); it.hasNext( ); j++ )
			{
				IComputedColumn compColumn = (IComputedColumn) it.next( );
				ResultFieldMetadata columnMetaData = new ResultFieldMetadata( ++count,
						compColumn.getName( ),
						compColumn.getName( ),
						DataType.getClass( compColumn.getDataType( ) ),
						null ,
						true );
				columnsList.add( columnMetaData );
			}
			return new ResultClass( columnsList );
		}
	}
	
	/**
	 *
	 */
	private final class CustomDataSet implements ICustomDataSet