根据同一个表中的另一列更改列值

I have the table

我有桌子

+---------------------+
| ID | Code | Amount -|
+---------------------+
| 1  | 101  | 1.2     | 
| 1  | 102  | 1.3     |
| 1  | 103  | 1.3     |
| 1  | 104  | 1.4     |
| 1  | 105  | 1.2     |
| 2  | 101  | 1.5     |
| 2  | 102  | 1.4     |
| 2  | 103  | 1.3     |
| 2  | 104  | 1.1     |
| 2  | 105  | 1.0     |
+---------------------+
+--------------------