I'm just getting my feet wet with the Drupal 7, Views 3 hook_views_data API which describes a table to Views.
I had a table like this :
create table tbl( myid varchar(30) COMMENT 'Primary key', myPrice float )
I was getting an error of this form when I was trying to display the view :
Undefined property: stdClass::$tbl_myPrice in views_handler_field_numeric->render() (line 75 of /drupal7/sites/all/modules/views/handlers/views_handler_field_numeric.inc).
Renaming the table to my_price solved the problem.