Question

I’m having problems trying to get a query like this

table answers

CREATE TABLE IF NOT EXISTS `rws_answers` (
  `id_answer` int(11) NOT NULL AUTO_INCREMENT,
  `id_question` int(11) DEFAULT NULL,
  `row_subject` varchar(255) NOT NULL,
  `column_subject` varchar(255) DEFAULT NULL,
  `answer_type` varchar(1) DEFAULT NULL,
  `score` int(5) DEFAULT '0',
  PRIMARY KEY (`id_answer`),
  KEY `IDX_51C8C33DE62CA5DB` (`id_question`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=765 ;

table reviews

CREATE TABLE IF NOT EXISTS `rws_reviews` (
  `id_review` int(11) unsigned NOT NULL,
  `id_client` varchar(36) NOT NULL DEFAULT '',
  `id_item` int(11) unsigned NOT NULL DEFAULT '0',
  `id_question` int(11) unsigned NOT NULL DEFAULT '0',
  `id_location` int(11) unsigned NOT NULL DEFAULT '0',
  `id_answer` int(11) unsigned NOT NULL DEFAULT '0',
  `value` text,
  `date_answered` datetime NOT NULL,
   PRIMARY KEY (`id_review`,`id_client`,`id_item`,`id_question`,`id_location`,`id_answer`),
  KEY `IDX_6868EE34943B391C` (`id_item`),
  KEY `IDX_6868EE34E62CA5DB` (`id_question`),
  KEY `IDX_6868EE34E45655E` (`id_location`),
  KEY `IDX_6868EE34FCEAFFC8` (`id_answer`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

what I need is to get all the id_answer in table answers that are and aren’t in table reviews
so if I try this sql

SELECT r.id_review, a.id_answer AS aa, r.id_answer AS ra, a.row_subject, r.id_location
FROM rws_answers a 
LEFT JOIN rws_reviews r USING(id_answer)
ORDER BY a.id_answer DESC

I get those rows, but because the reviews table can have different id_location I need to filter them so I add to the query this

SELECT r.id_review, a.id_answer AS aa, r.id_answer AS ra, a.row_subject, r.id_location
FROM rws_answers a 
LEFT JOIN rws_reviews r USING(id_answer)
WHERE r.id_location = 1
ORDER BY a.id_answer DESC

but then all my answers that aren’t in reviews table don’t show anymore, I had try any sort of combination without result, can anyone be so kind to try to help me out or maybe suggest me a different way of doing the query, I have more than 3 day trying, readying, doing example, don’t know what else to do, thanks!

Answer 1

You can convert the USING clause to an ON clause, and merge the WHERE clause into it:

LEFT JOIN rws_reviews r ON r.id_answer = a.id_answer AND r.id_location = 1