GROUP BY in hook_views_query_alter() doesn't work as expected.

I've got a view that is showing duplicates and want to easily just modify the query generated by views to group by a specific field. Looking at the query that views creates, I can easily accomplish this by just adding a group by on a specific field, which in this case is not a field that is specified as a field in the Views UI.

It would seem that you should be able to just do a hook_views_query_alter() to adjust the query I need. This is what I did:

function hook_views_query_alter(&$view, &$query) {
  // I only know of this field alias by viewing the query views creates, I did not explicitly add this field.
  $query->add_groupby('myfield_alias'); 
}

Unfortunately views does not respect adding a groupby like this due to requiring HAVING aggregates. I modified views_plugin_query_default.inc to allow this groupby without aggregates. GROUP BY statements do not require aggregates, views shouldn't either. I also added a ternary for setting the fields to groupby.

Patch to come in the comments.