，您不能直接将Db2表中的列类型从CLOB更改为BLOB！
ALTER TABLE ALTER COLUMN SET数据类型语句仅允许更改以下数据类型的列：
字符
数值
二进制

you can't directly change the column type in your Db2 table from CLOB to BLOB!! The ALTER TABLE ALTER COLUMN SET DATA TYPE statement allows changing columns of the following data types only: Character Numeric Binary