https://codelog.me/zh/tags/%E6%95%B0%E6%8D%AE%E5%BA%93/Recent content in 数据库 on Code LogHugozh-CNWed, 12 Apr 2017 23:15:36 +0800https://codelog.me/zh/posts/sql-join-in-detail/Wed, 12 Apr 2017 23:15:36 +0800https://codelog.me/zh/posts/sql-join-in-detail/<p>如果你也曾经被SQL语言中各种Join操作：Left Join, Right Join, Inner Join等搞晕了头，那么这篇文章比较适合你。本文通过维恩图演示各种Join语句的执行效果，简单直白容易记忆。<a href="https://blog.codinghorror.com/a-visual-explanation-of-sql-joins/">原文见</a></p> <p>假如有两张表 <strong>Table A</strong> 和 <strong>Table B</strong>, 表数据如下: Table A:</p> <table> <thead> <tr> <th>id</th> <th>name</th> </tr> </thead> <tbody> <tr> <td>1</td> <td>Pirate</td> </tr> <tr> <td>2</td> <td>Monkey</td> </tr> <tr> <td>3</td> <td>Ninja</td> </tr> <tr> <td>4</td> <td>Spaghetti</td> </tr> </tbody> </table> <p>Table B:</p> <table> <thead> <tr> <th>id</th> <th>name</th> </tr> </thead> <tbody> <tr> <td>1</td> <td>Rutabaga</td> </tr> <tr> <td>2</td> <td>Pirate</td> </tr> <tr> <td>3</td> <td>Darth Vader</td> </tr> <tr> <td>4</td> <td>Ninja</td> </tr> </tbody> </table> <p>下面我们来看看各种Join的执行效果</p>