Idea to help us to use sqlExp

[GoogleCodeExporter]

1.ZF 1.12
2.ZF DATAGRID 0.8 (proud)
FIRST
On Grid Source Array php on line 477
Will it be possible to improve your comment like this 
throw new Bvb_Grid_Exception("setSqlExp Operation $operation not found");
It will show us it's a sqlExp problem and what we put in !

SECOND
I've try to put "SUM" as a name for the colums with :
$options["totalType"]["functions"]= array('decorator' => 'Total');
I never arrive to do that ! How to do please ?

THANKS

Original issue reported on code.google.com by sebastie...@gmail.com on 24 Jul 2012 at 7:32