需要查找所有带有意大利语翻译的单词,如果意大利语不存在,则需要西类牙语(默认语言)。 我不能使用多个查询,并且存在条件(技术限制)
话
id|name
-------
1|Dog
2|Cat
翻译
id|word_id|translation|language
-------------------------------
1| 1| Perro|es
2| 1| Cane |it
3| 2| Gatto|es
结果:
id|name|translation|language
1| Dog| Cane|it
2| Cat| Gatto|es
SELECT * FROM words LEFT JOIN translation ON words.id = translation.word_id WHERE language = 'it' OR (language = 'es' AND NOT EXISTS(SELECT * FROM translation WHERE word_id = words.id AND language = 'it'))
此代码返回我需要的所有内容,但我无法在我的情况下使用 where contains 条件
最佳答案
我会将 words
表加入 translations
表两次,每种语言一次:
SELECT w.id,
w.name,
COALESCE(it.translation, es.translation) AS translation,
COALESCE(it.language, es.language) AS language
FROM words w
LEFT JOIN translation it ON w.id = it.word_id AND it.language = 'it'
LEFT JOIN translation es ON w.id = es.word_id AND es.language = 'es'
关于mysql - 具有默认关系的左连接,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/51046859/