select dbms_lob.substr(IOF_CONTEXT) FROM IM_OPERATION_FLOW WHERE IOF_BATCHNO='3652';
转换的时候如果报错
[Err] ORA-06502: PL/SQL: 数字或值错误 : raw variable length too long
使用下面方法截取字符串
SELECT trim(dbms_lob.substr(IOF_CONTEXT,2000)) FROM IM_OPERATION_FLOW WHERE IOF_BATCHNO='3652'