Returns a reference to the group-by array for this query.
Because this method returns by reference, alter hooks may edit the group-by array directly to make their changes. If just adding additional grouping fields, however, the use of groupBy() is preferred.
Note that this method must be called by reference as well:
$fields =& $query->getGroupBy();
A reference to the group-by array structure.:
includes/ database/ select.inc, line 121
- Interface definition for a Select Query object.
public function &getGroupBy();