Question

我是SQL的新手。这没有任何结果......

SELECT media.id as mediaid, media.title as mediatitle, 
  media.description as mediadescription, media.date as mediadate, 
  media.duration, media.price as mediaprice, media.thumburl as thumburl, 
  presenters.f_name as firstname, presenters.l_name as lastname, 
  presenters.credentials 
FROM `media` 
WHERE media.title = 'Code of Ethical Conduct' 
LEFT JOIN `presenters` ON presenters.fkMediaID = media.id

但在我添加演示者部分之前，它工作得很好......

SELECT media.id as mediaid, media.title as mediatitle, 
  media.description as mediadescription, media.date as mediadate, 
  media.duration, media.price as mediaprice, media.thumburl as thumburl 
FROM `media` 
WHERE media.title = 'Code of Ethical Conduct'

任何想法为什么？

Answer 1

WHERE子句最后一次

所以它将来自媒体LEFT JOIN演示者.....

WHERE media.title ....

Answer 2

LEFT JOIN部分应该是之前 WHERE部分。

SELECT media.id as mediaid, media.title as mediatitle,
    media.description as mediadescription, media.date as mediadate,
    media.duration, media.price as mediaprice, media.thumburl as thumburl,
    presenters.f_name as firstname, presenters.l_name as lastname,
    presenters.credentials
FROM media
LEFT JOIN presenters ON presenters.fkMediaID = media.id
WHERE media.title = 'Code of Ethical Conduct'

基本的SQL东西......左连接

2 个答案: