mysql實現full join

本文轉載自查看原文 2017-04-08 12:15 5364 mysql

呵呵,,,有個坑,,mysql默認不支持full join 是吧. 什么是full join呢就是left+right join 可以使用union聯表解決這個問題
union 鏈接 http://www.php20.com/forum.php?m ... &extra=page%3D1
原表鏈接 http://www.php20.com/forum.php?m ... &extra=page%3D1咱們的鏈接如下

[SQL] 純文本查看 復制代碼

 
                 select 
                 b.title,b.content,a.class_name,a.id  
                 as 
                 classid  
                 from 
                 news_class  
                 as 
                 a  
                 left 
                 join 
                 news  
                 as 
                 b  
                 on 
                 a.id=b.id 
                
 
                 union 
                 all   
                
 
                 select 
                 b.title,b.content,a.class_name,a.id  
                 as 
                 classid  
                 from 
                 news_class  
                 as 
                 a  
                 right 
                 join 
                 news  
                 as 
                 b  
                 on 
                 a.id=b.id; 
                

結果right和left 的合一塊去了. 所以出現了重復內容

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