在列中更新XML字符串的一部分

Table a:

表一:

+------+------+------+--------------------------------------+
| col1 | col2 | col3 | Col4                                 |
+------+------+------+--------------------------------------+
|    1 | A    | E    |<?xml version .....<v> "OOOO"</v></vs>|  
|    2 | B    | F    |<?xml version .....<v> "KKKK"</v></vs>|      
|    3 | C    | G    |<?xml version .....<v> "LLLL"</v></vs>|   
|    4 | B    | E    |<?xml version .....<v> "MMMM"</v></vs>|     
|    5 | T    | G    |<?xml version .....<v> "NNNN"</v></vs>| 
+------+------+------+--------------------------------------+
+------+------+------+--------