GROUP BY - do not group NULL

Question

I\'m trying to figure out a way to return results by using the group by function.

GROUP BY is working as expected, but my question is: Is it possible to have group b

Answer 1

Maybe faster version of previous solution in case you have unique identifier in table1 (let suppose it is table1.id) :

SELECT `table1`.*, 
    GROUP_CONCAT(id SEPARATOR ',') AS `children_ids`,
    IF(ISNULL(ancestor),table1.id,NULL) as `do_not_group_on_null_ancestor`
FROM `table1` 
WHERE (enabled = 1) 
GROUP BY `ancestor`, `do_not_group_on_null_ancestor`