https://codelog.me/en/categories/database/Recent content in Database on Code LogHugoen-USWed, 12 Apr 2017 23:15:36 +0800https://codelog.me/en/posts/sql-join-in-detail/Wed, 12 Apr 2017 23:15:36 +0800https://codelog.me/en/posts/sql-join-in-detail/<p>If you&rsquo;ve ever been confused by the various join operations in SQL — Left Join, Right Join, Inner Join, and so on — then this article is for you. It demonstrates the effect of each join statement with Venn diagrams, which is straightforward and easy to remember. <a href="https://blog.codinghorror.com/a-visual-explanation-of-sql-joins/">Original post</a></p> <p>Suppose there are two tables, <strong>Table A</strong> and <strong>Table B</strong>, with the following data: 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>Let&rsquo;s look at the effect of each join.</p>