sql 連線查詢例項（left join）三表連線查詢

當前有三個表 :

• CommercialNews as a
• WebCommunity as b
• CommercialNewsOriginalWebsite as c

條件是  a.idcommunity = b.webid , a.originalWebid = c.idnumber  

要求從三個表裡查出符合上述條件的 以下欄位，並以 a.creadate 進行desc降序排序： 

• a.idnumber
• a.creadate
• a.description
• a.fileurl
• a.title
• b.wname
• c.webName
• c.logo 

最後sql語句為：

select a.idnumber,a.creadate,a.description,a.fileurl,a.title,b.wname,c.webName,c.logo 
from commercialnews as a 
left join webcommunity as b on a.idcommunity = b.webid 
left join CommercialNewsOriginalWebsite as c on a.originalWebid = c.idnumber order by a.creadate desc;