mysql right join not working as expected - mysql

Question

When I use right join I get the same results as using left join or just join. Can anyone show me where I have gone wrong?
I have 3 tables as follows:
langugages
id
code eg "hu","en"
language_default
id
text
language_translations
id
lang_id (FK the id of the language in the languages table)
default_lang_id (FK the id of the text in the languages_default table)
text (the translation)
When I execute the following query, I expect to get all of the hungarian translations from the language_translations table and all of the text fields from the language_default table with a null value where there is no hungarian translation.
SELECT `language_translations`.`text`
, `language_default`.`text`
FROM `languages`
, `language_translations`
RIGHT JOIN `language_default` ON `language_default`.`id` = `language_translations`.`default_lang_id`
WHERE `languages`.`code` = 'hu'
AND `languages`.`id` = `language_translations`.`lang_id`
Instead I only get text from the language_default table where there are translations for that text in the tranlsation table. I would expect that behaviour from a left join or normal join but not a right join. Any ideas why I am not getting all of the entries from the langugage_defailt table?

Answer 1

First of all you are using combination of normal join and rights join in wrong way. You can use as per below query.
2nd thing right join means you will get all record from right side and corresponding records from left side and if left side does not have corresponding record then it will show NULL.
Left join is its reverse.
Normal join or comma join will provide only common rows.
So if your tables only have common rows then all joins will provide same results.
SELECT
`language_translations`.`text` , `language_default`.`text`
FROM `languages` AS l
JOIN `language_translations` AS t
ON l.`id` = t.`lang_id` AND l.`code` = 'hu'
RIGHT JOIN `language_default` AS d
ON d.`id` = t.`default_lang_id`;

Answer 2

Don't mix implicit joins and explicit joins. A simple rule is: don't use , in the from clause. The following restructures your query to use left outer join:
SELECT `language_translations`.`text`, ld.`text`
FROM language_default ld left outer join
language_translations lt
on ld.`id` = lt.`default_lang_id` left outer join
`languages` l
on l.`id` = lt.`lang_id` and l.`code` = 'hu' ;
When using outer joins, you need to be very careful about where additional conditions go. Conditions on the driving table (the first a left outer join, the last for a right outer join) can go in the where clause. For other tables, the conditions should go in the on clause. Otherwise, they turn the outer join into an inner for the simple reason that (almost) any comparison to NULL is equivalent to false.