关系数据库内连接、左连接、右连接图示说明

很多次被问起 内连接、左连接 、 右连接相关的问题。每次的回答都不是很明确，前端时间看到一篇文章用绘图的方式给出了明确的回答。原文的链接为http://www.codinghorror.com/blog/archives/000976.html
内连接 Inner join


SELECT * FROM TableA


INNER JOIN TableB


ON TableA.name = TableB.name



全外连接 Full outer join



SELECT * FROM TableA


FULL OUTER JOIN TableB


ON TableA.name = TableB.name



左外连接 Left outer join



SELECT * FROM TableA


LEFT OUTER JOIN TableB


ON TableA.name = TableB.name



表A中排除了B中的记录


SELECT * FROM TableA


LEFT OUTER JOIN TableB


ON TableA.name = TableB.name


WHERE TableB.id IS null





A表和B表中互不相等


SELECT * FROM TableA


FULL OUTER JOIN TableB


ON TableA.name = TableB.name


WHERE TableA.id IS null


OR TableB.id IS null







相关资料
The dangerous subtleties of LEFT JOIN and COUNT() in SQL