4.软考数据库(一)
其他
2019-10-24 12:40:33
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4.01 数据库前言
![](https://img-blog.csdnimg.cn/20191015145048322.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
4.02 数据库三级模式两级映射
![](https://img-blog.csdnimg.cn/20191015145921167.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
4.03 数据库设计过程说明
![](https://img-blog.csdnimg.cn/20191015150429489.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
4.04 ER模型
先画局部ER图
![](https://img-blog.csdnimg.cn/2019101515072314.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015151140689.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
结构冲突:在两个不同的系统里
![](https://img-blog.csdnimg.cn/20191015151958502.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
4.05 关系代数(综合,选择题)
![](https://img-blog.csdnimg.cn/20191015152503758.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015152734598.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015152957440.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
联接 不写条件就是自然联接 自动寻找相同的字段
![](https://img-blog.csdnimg.cn/20191015153346309.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015153638992.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
4.06 规范化函数理论——函数依赖
![](https://img-blog.csdnimg.cn/20191015161844338.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015162026276.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
4.07 规范化的理论价值与用途(非常重要)
![](https://img-blog.csdnimg.cn/20191015162739639.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
4.08 规范化理论——求候选关键字
![](https://img-blog.csdnimg.cn/20191015163426597.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
图示法----求候选键非常的方便
![](https://img-blog.csdnimg.cn/20191015163547435.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015164141597.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015164515215.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
4.09 规范化理论——范式(每次必考)
一般做到第三范式就可以了,范式提高,性能会下降
原子值:是不能拆分的值
![](https://img-blog.csdnimg.cn/20191015165632189.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
第一范式
![](https://img-blog.csdnimg.cn/20191015165840939.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
第二范式
![](https://img-blog.csdnimg.cn/20191015170053386.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015170507942.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
第三范式--单属性是不可能有部分函数依赖的关系存在的
![](https://img-blog.csdnimg.cn/20191015170812882.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
![](https://img-blog.csdnimg.cn/20191015171010593.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
BCNF BC范式
![](https://img-blog.csdnimg.cn/20191015172019932.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NodWp1a3VfX19f,size_16,color_FFFFFF,t_70)
转载自blog.csdn.net/shujuku____/article/details/102567405