enhance groupby behaviour with sql_mode=only_full_group_by?

[blueo]

Affected Version

SS4 with mysql >=5.7.5

Description

As mentioned in #5451 and #9721 MYSQL 5.7.5 and above has stricter requirements for queries using group by.

So it seems there is a little bit of a foot-gun for people when doing something like:

$list = MyDataObject::get();
$list->alterDataQuery(static function (DataQuery $query) use ($value) {
    return $query
        ->groupby('ID');
});

As the ORM will get all fields by default, this will result in an error as discussed a bit here: #6892.

Given it feels quite natural for people to take a the ORM as a start point and tweak it slightly like this could we do anything to help this situation?

Ideas include:

• adding a getQueriedColumns method on DataQuery. Currently setQueriedColumns but it seems difficult to access the existing queried columns without diving into a manipulator class. This allows people to add to the groupby if needed?
• automatically add select columns when using groupby? This is probably not a good idea/difficult but just putting it out there
• add some suggestions to the error?