Counting a left join depending on other left join - mysql

Question

I have this query:
SELECT options.id, options.text,
COUNT(options2.id) AS num_children
FROM options
JOIN history_uids AS uids
ON uids.uid = options.id
LEFT JOIN options AS options2
ON (options.id = options2.id_parent)
LEFT JOIN history_uids AS uids1
ON uids1.uid = options2.id
WHERE (
options.id = 25
AND (uids1.active = 1 OR
options2.id IS NULL) # Problem
)
GROUP BY `options`.`id`
There is an options table, and another, history_uids, which has a column named uid with the id of every options, and an active column set to 1 or 0.
I am expecting to get a result with:
The ID and the text of the option which has the id 25, and which has active set to 1 in history_uids.
The number of options which have an id_parent equal to the id (25) and for which active in history_uids is set to 1
So whatever is this number I should get my row if it has active set to 1. I cannot understand how to achieve this: I wanna set as last condition uids1.active = 1 OR "options2 doesn't exist", but to get this I should have my active condition in the ON of options2, which is not possible because at that moment the table history_uids is not yet referenced...
In my case the row has active set to 1 and has 5 children with active set to 0, so I should get my row with num_children set at 0. Instead whatever combination I do in the JOIN or the WHERE I get either num_children set to 5 or no result at all.
Thanks for your help (and for reading!)
Here is the full structure and data for testing:
CREATE TABLE `history_uids` (
`uid` int(10) NOT NULL,
`active` tinyint(1) NOT NULL DEFAULT '1'
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `history_uids` (`uid`, `active`) VALUES
(1, 1),
(2, 0),
(3, 0),
(4, 0),
(5, 0),
(6, 0);
CREATE TABLE `options` (
`id` int(10) NOT NULL,
`id_parent` int(10) DEFAULT NULL,
`text` varchar(255) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `options` (`id`, `id_parent`, `text`) VALUES
(1, NULL, 'parent active'),
(2, 1, 'child 1 inactive'),
(3, 1, 'child 2 inactive'),
(4, 1, 'child 3 inactive'),
(5, 1, 'child 4 inactive'),
(6, 1, 'child 5 inactive');
ALTER TABLE `history_uids`
ADD PRIMARY KEY (`uid`);
ALTER TABLE `options`
ADD PRIMARY KEY (`id`),
ADD KEY `id_parent` (`id_parent`);
ALTER TABLE `options`
ADD CONSTRAINT `ibfk_3` FOREIGN KEY (`id_parent`) REFERENCES `options` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
ADD CONSTRAINT `ibfk_4` FOREIGN KEY (`id`) REFERENCES `history_uids` (`uid`) ON DELETE CASCADE ON UPDATE CASCADE;

Answer 1

You need to put the active test for the child row into the ON clause, so that inactive rows will be filtered out of the LEFT JOIN. And you should be counting uids1.uid, not options2.id, since the inactive rows aren't filtered out until you join with uids1.
SELECT options.id, options.text,
COUNT(uids1.uid) AS num_children
FROM options
JOIN history_uids AS uids
ON uids.uid = options.id
LEFT JOIN options AS options2
ON (options.id = options2.id_parent)
LEFT JOIN history_uids AS uids1
ON uids1.uid = options2.id and uids1.active = 1
WHERE
uids.active = 1
GROUP BY `options`.`id`
DEMO