I have a database structure like this:
Countries
CREATE TABLE IF NOT EXISTS `countries` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`code` varchar(2) COLLATE utf8_unicode_ci NOT NULL,
`is_active` tinyint(1) NOT NULL,
`created_at` datetime NOT NULL,
`updated_at` datetime NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `UNIQ_5D66EBAD77153098` (`code`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
Countries Language
CREATE TABLE IF NOT EXISTS `country_languages` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`language_id` int(11) DEFAULT NULL,
`country_id` int(11) DEFAULT NULL,
`name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`created_at` datetime NOT NULL,
`updated_at` datetime NOT NULL,
PRIMARY KEY (`id`),
KEY `IDX_1532561982F1BAF4` (`language_id`),
KEY `IDX_15325619F92F3E70` (`country_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
Language
CREATE TABLE IF NOT EXISTS `languages` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`iso` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`active` tinyint(1) NOT NULL DEFAULT '1',
`is_primary` tinyint(1) DEFAULT NULL,
`created_at` datetime NOT NULL,
`updated_at` datetime NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `UNIQ_A0D153795E237E06` (`name`),
UNIQUE KEY `UNIQ_A0D1537961587F41` (`iso`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
And the data for languages table:
id name iso
----------------------
1 English en
2 German de
3 Italian it
And country table:
id code
----------------
1 ie
And country languages table
id country_id language_id name
----------------------------------------------
1 1 1 Ireland in English
2 1 2 Ireland in German
I am trying to write a query that will return the following result in order to be able to display it. (if possible)
(Language) (Country name)
English Ireland in English
German Ireland in German
Italian #NULL OR EMPTY STRING
And second I am trying to understand if it is possible to set for example english as the default language and when content for language with id 3 (Italian) is not present the default should fallback in as a result like this:
(Language) (Country name)
English Ireland in English
German Ireland in German
Italian Ireland in English #please note language id is 3 -> Italian.
okay, so the following query can probably be done without a subquery but with a join instead. I'd trust the query optimizer does this, but I wouldn't be too sure.
SELECT l.name as language,
(SELECT cl.name
FROM country_languages cl
WHERE cl.country_id=[the wanted country id]
ORDER BY cl.language_id=l.id DESC,
cl.language_id=1 DESC
LIMIT 1) as country_name
FROM languages l
In this version language_id 1 is used as the prefered fallback, you could probably add more languages in a similar manner. Using FIND_IN_SET instead as a second order criterion would work as well (FIND_IN_SET(cl.language_id,'1,2,3') DESC or whatever order you'd prefer).
Of course this query right now is for a fixed country_id. It could be extended in a similar manner for multiple countries with another join:
SELECT l.name as language,
(SELECT cl.name
FROM country_languages cl
WHERE cl.country_id=c.id
ORDER BY cl.language_id=l.id DESC,
cl.language_id=1 DESC
LIMIT 1) as country_name
FROM countries c
JOIN languages l
an alternative to subqueries would be to join the country_languages twice, and just select the first one not being null (which is probably one of the cleaner solutions):
SELECT l.name as language,
COALESCE(first.name, second.name) as country_name
FROM countries c
JOIN languages l
LEFT JOIN country_languages first ON
(first.country_id=c.id AND first.language_id=l.id)
LEFT JOIN country_languages second ON
(second.country_id=c.id AND second.language_id=1)
If language id 1 is your fallback language. This can be expanded as well to provide multiple fallback languages ...
Here is the query for first part using joins:
SELECT `country_languages`.id, `country_languages`.country_id,`country_languages`.language_id, `country_languages`.name FROM `countries` left join country_languages on `countries`.id=`country_languages`.`country_id`
You can declare a status column in countries languages table and set status as 0,1,2 to mark priority as to how they will be fetched.