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                            # DBMS 中的多值依賴

> 原文： [https://beginnersbook.com/2015/04/multivalued-dependency-in-dbms/](https://beginnersbook.com/2015/04/multivalued-dependency-in-dbms/)

當表中存在多個**獨立**多值屬性時，會發生多值依賴。

**例如**：考慮一家自行車制造公司，每年在每個車型中生產兩種顏色（黑色和白色）。

| `bike_model` | `manuf_year` | `color` |
| --- | --- | --- |
| M1001 | 2007 | Black |
| M1001 | 2007 | Red |
| M2012 | 2008 | Black |
| M2012 | 2008 | Red |
| M2222 | 2009 | Black |
| M2222 | 2009 | Red |

這里的列`manuf_year`和顏色彼此獨立并依賴于`bike_model`。在這種情況下，這兩列可以說是多值的，取決于`bike_model`。這些依賴關系可以表示如下：

```
bike_model ->> manuf_year

bike_model ->> color
```
                    
                
        
                
            
        
                
    
                
    
                
        
                
    
                

                







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