【数据库系统概论】考研附加部分重点分析【附加】

布满荆棘的人生 2023-07-13 04:28 49阅读 0赞

### 文章目录 ###

*  (附加) 【关系查询处理与优化】
 *   *  1.【选择操作】
     *  2.【连接操作】
     *  3.【读取时间】
     *  4.【重点例题】

# (附加) 【关系查询处理与优化】 #

## 1.【选择操作】 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI1NjAxMzQ1_size_16_color_FFFFFF_t_70]

## 2.【连接操作】 ##

![在这里插入图片描述][20200310213311600.png]

## 3.【读取时间】 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI1NjAxMzQ1_size_16_color_FFFFFF_t_70 1]

## 4.【重点例题】 ##

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[20200310213311600.png]: https://img-blog.csdnimg.cn/20200310213311600.png
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