oracle 表字段varchar2 修改为 clob 备忘

create table OPT_LOG
(
  opercontent VARCHAR2(500)
)

alter table opt_log add tmp_opercontent clob;
update opt_log s set s.tmp_opercontent = s.opercontent;
commit;
alter table opt_log drop column opercontent;
alter table opt_log rename column tmp_opercontent to opercontent;