【问题标题】：Joining two tables with FULL JOIN使用 FULL JOIN 连接两个表
【发布时间】：2014-02-03 05:45:54
【问题描述】：

我有两张桌子master1 和master2：

insert into master1 
(name,address,books,laptop,id,college) values
(ratan,mg road,rajbook,hp,id334,xxx)
(sham,r t nagar,malbook,ibm,id335,xxx)
(ram,shiva road,kalbook,hp,id336,xxx)
(farooq,uday road,rabook,hp,id337,xxx)
(sharukh,kr road,kambook,sony,id338,xxx)

insert into master2
(nam,lappy,idd,coll) values
(ratan,hp,877,ratan college)
(ram,sony,877,ram college)

我想要：

select name, address, books, laptop, id, college, nam, lappy
  from master1 LEFT JOIN master2
 where master1.college=master2.coll

输出应该是：

(name,address,books,laptop,id,college,nam,lappy
(ratan,mg road,rajbook,hp,id334,xxx,keshav,hp)
(sham,r t nagar,malbook,ibm,id335,xxx,null,null)
(ram,shiva road,kalbook,hp,id336,xxx,null.null)
(farooq,uday road,rabook,hp,id337,xxx,null,null)
(sharukh,kr road,kambook,sony,id338,xxx,ram,sony)

【问题讨论】：

问题是什么？
您显示了一个没有 ON 或 USING 子句的 LEFT JOIN；你需要添加一个。标题中提到 FULL JOIN 的原因是什么？它似乎与您想要的输出无关。

标签： mysql sql join

【解决方案1】：

WHERE 不正确，而您缺少 ON 部分 JOIN 子句。

select name,address,books,laptop,id,college,nam,lappy
from master1
left join master2 on master1.college = master2.coll

【讨论】：

感谢您的回复，对我有帮助

【解决方案2】：

使用ON

SELECT name,address,books,laptop,id,college,nam,lappy
FROM master1
LEFT OUTER JOIN master2
ON master1.college = master2.coll

【讨论】：

【解决方案3】：

Select name
      ,address
      ,books
      ,laptop
      ,id
      ,college
      ,nam
      ,lappy
From master1
LEFT JOIN master2 ON 
      master1.college=master2.coll

你的左连接是错误的，我的格式是这样的

Joins Tutorial

LEFT JOIN and RIGHT JOIN Optimization

你的输出如下

Working SQL Fiddle

【讨论】：