Styjun

I'm trying to figure out how to use UNION with the same JOIN and not to fall into #2014 - Commands out of sync.

I have created four simple tables and wrote simplified code for them. The main idea is to get each sword, gun and hat which have 'best' in name + if the owner of these is cool.

SELECT pirate_id, sword, null AS gun, null AS hat, legs = 1 AS is_cool FROM swords as t1
LEFT JOIN
(SELECT legs, pirate_id as pid FROM body_parts) AS t2
ON t1.pirate_id = t2.pid
WHERE sword LIKE '%best%'

UNION
SELECT pirate_id, null AS sword, gun, null AS hat, legs = 1 AS is_cool FROM guns as t3
LEFT JOIN
(SELECT legs, pirate_id as pid FROM body_parts) AS t4
ON t3.pirate_id = t4.pid
WHERE gun LIKE '%best%' 

UNION
SELECT pirate_id, null AS sword, null AS gun, hat, legs = 1 AS is_cool FROM hats as t5
LEFT JOIN
(SELECT legs, pirate_id as pid FROM body_parts) AS t6
ON t5.pirate_id = t6.pid
WHERE hat LIKE '%best%' 

ORDER BY is_cool DESC, pirate_id ASC

Currently I have to repeat JOIN each time I have to UNION. I hope there is a better way...

TABLES CREATION:

CREATE TABLE IF NOT EXISTS `body_parts` (
 `pirate_id` int(11) NOT NULL,
 `legs` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `body_parts` (`pirate_id`, `legs`) VALUES
(1, 0),
(2, 1),
(3, 2);

CREATE TABLE IF NOT EXISTS `guns` (
 `pirate_id` int(11) NOT NULL,
 `gun` varchar(100) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `guns` (`pirate_id`, `gun`) VALUES
(1, 'best 1');

CREATE TABLE IF NOT EXISTS `hats` (
 `pirate_id` int(11) NOT NULL,
 `hat` varchar(100) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `hats` (`pirate_id`, `hat`) VALUES
(2, 'best 2');

CREATE TABLE IF NOT EXISTS `swords` (
 `pirate_id` int(11) NOT NULL,
 `sword` varchar(100) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `swords` (`pirate_id`, `sword`) VALUES
(3, 'best 3');

You could use a single left join changing the using a subquery

 select t1.pirate_id, t1.sword, t1.gun, t1.hat, t2.legs=1 is_cool

 from (
 SELECT pirate_id, sword, null AS gun, null AS hat 
 FROM swords 
 WHERE sword LIKE '%best%'

 UNION 

 SELECT pirate_id, null, gun, null
 FROM guns 
 WHERE gun LIKE '%best%' 

 UNION 
 SELECT pirate_id, null, null, hat
 FROM hats 
 WHERE hat LIKE '%best%'
 ) t1 
 LEFT JOIN (
 SELECT legs, pirate_id 
 FROM body_parts
 ) t2 ON t2.pirate_id = t1.pirate_id
 ORDER BY is_cool DESC, pirate_id ASC