Question

I have a table like this (shown without any grouping) and am using MySQL 5.5.

mytable
================================================================================
id    type     parent_type     type_id     content                     parent_id
================================================================================
1     type1    NULL            3           john's test content         NULL
2     type1    NULL            3           hi there, this is john      NULL
3     type2    ptype1          4           [e-mail]              2
4     type3    ptype1          2           John Smith                  2
5     type3    ptype1          8           Sean John John              10
6     type3    ptype1          13          John Smith                  11

I would like to group all the rows first by by parent_type and parent_id then type and type_id. Parent_type and parent_id can be some times NULL, but NULLs should not be grouped.

Here’s what I am trying at the moment:

SELECT id, type, IFNULL(parent_type, UUID()) as parent_type, type_id, content, IFNULL(parent_id, UUID()) as parent_id
FROM mytable
WHERE MATCH(content) AGAINST('john*' IN BOOLEAN MODE) GROUP BY parent_type, parent_id, type_index, type_id LIMIT 10 ;

But the desired result is, I want the result to be grouped by parent_type and parent_id first, and then grouped by parent_type and parent_id like so:

mytable
================================================================================
id    type     parent_type     type_id     content                     parent_id
================================================================================
1     type1    NULL            3           john's test content         NULL
3     type2    ptype1          4           [e-mail]              2
5     type3    ptype1          8           Sean John John              10
6     type3    ptype1          13          John Smith                  11

How can this be done?

Answer 1

Using a subquery did the trick:

SELECT *
FROM (
     SELECT id, type, type_id, content, MATCH(content) AGAINST('john') as relevance, IFNULL(parent_type, UUID()) as parent_type, IFNULL(parent_id, UUID()) as parent_id
     FROM mytable WHERE MATCH(content) AGAINST('john*' IN BOOLEAN MODE) GROUP BY parent_type, parent_id
) as search
GROUP BY search.type, search.type_id DESC  LIMIT 10 ;