MySQL query with reference to many to many table - mysql

Question

Assuming the following tables:
area
-id
-title
properties
-id
-title
-area_id
categories
-id
-title
properties_categories
-property_id
-category_id
The following query is very close to the correct answer but is not correct. Could you advise what the correct query is?
select a.id, a.title, count(p.id)
FROM area AS a,properties AS p, properties_categories AS pc
WHERE a.id = p.area_id
AND pc.category_id IN (1,2,3)
AND pc.property_id = p.id
GROUP BY a.id;
OR
SELECT A.id, A.title, COUNT(B.id)
FROM area A LEFT JOIN properties B
ON A.id=B.area_id
JOIN properties_categories C
ON C.property_id=B.id
WHERE C.category_id IN (1,2,3)
GROUP BY A.id, A.title;
If I write a query where the following only draws from the area and properties table you have the correct results.
SELECT A.id, A.title, COUNT(B.id) FROM area A LEFT JOIN properties B ON A.id=B.area_id GROUP BY A.id, A.title
Here is the data dump to experiment with:
CREATE TABLE `area` (
`id` int(10) UNSIGNED NOT NULL,
`title` varchar(255) COLLATE utf8_unicode_ci NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
INSERT INTO `area` (`id`, `title`) VALUES
(2, 'Test1'),
(3, 'Test2'),
(4, 'Test3'),
(5, 'Test4'),
(6, 'Test5');
CREATE TABLE `categories` (
`id` int(10) UNSIGNED NOT NULL,
`title` varchar(255) COLLATE utf8_unicode_ci NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
INSERT INTO `categories` (`id`, `title`) VALUES
(1, 'Category A'),
(2, 'Category B'),
(3, 'Category C'),
(4, 'Category D'),
(5, 'Category E'),
(6, 'Category F');
CREATE TABLE `properties` (
`id` int(11) NOT NULL,
`name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`area_id` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
INSERT INTO `properties` (`id`, `name`, `area_id`) VALUES
(2, 'Property A', 2),
(3, 'Property B', 2),
(4, 'Property C', 2),
(5, 'Property D', 2),
(7, 'Property E', 2),
(8, 'Property F', 2),
(10, 'Property G', 2),
(11, 'Property H', 2),
(12, 'Property I', 2),
(13, 'Property J', 2),
(14, 'Property K', 2),
(19, 'Property L', 2),
(20, 'Property M', 4),
(21, 'Property O', 2),
(22, 'Property P', 2),
(23, 'Property Q', 2),
(24, 'Property R', 2),
(27, 'Property S', NULL),
(29, 'Property T', 2),
(30, 'Property U', 2),
(32, 'Property V', 2),
(33, 'Property W', 2),
(34, 'Property X', 5),
(35, 'Property Y', 5),
(36, 'Property Z', 5),
(37, 'Property A1', 5),
(38, 'Property A2', 3),
(39, 'Property A3', 6);
CREATE TABLE `properties_categories` (
`category_id` int(11) NOT NULL,
`property_id` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
INSERT INTO `properties_categories` (`category_id`, `property_id`) VALUES
(2, 2),
(6, 2),
(2, 3),
(6, 3),
(2, 4),
(6, 4),
(2, 5),
(6, 5),
(2, 7),
(6, 7),
(2, 8),
(6, 8),
(2, 10),
(6, 10),
(2, 11),
(6, 11),
(2, 12),
(6, 12),
(2, 13),
(6, 13),
(2, 14),
(6, 14),
(5, 7),
(5, 3),
(5, 14),
(5, 4),
(5, 12),
(5, 11),
(5, 13),
(5, 5),
(5, 10),
(5, 8),
(2, 20),
(3, 20),
(2, 19),
(6, 19),
(2, 21),
(2, 22),
(2, 23),
(5, 23),
(6, 23),
(1, 22),
(2, 24),
(6, 24),
(2, 29),
(2, 30),
(5, 30),
(2, 33),
(5, 33),
(6, 33),
(2, 32),
(5, 32),
(6, 32),
(1, 34),
(2, 34),
(3, 34),
(4, 34),
(2, 35),
(5, 35),
(2, 36),
(4, 36),
(5, 36),
(2, 37),
(4, 37),
(5, 37),
(2, 38),
(2, 39),
(4, 39),
(5, 39),
(1, 39),
(5, 24),
(4, 38);

Answer 1

Try this:
SELECT A.id, A.title, COUNT(B.id)
FROM area A LEFT JOIN properties B
ON A.id=B.area_id
JOIN properties_categories C
ON C.property_id=B.id
WHERE C.category_id IN (1,2,3)
GROUP BY A.id, A.title;
See MySQL Join Made Easy for insights on using joins in mysql.