将NVARCHAR2类型改为clob字段类型
alter table DM_SELF_PROGRAM rename column document to my_document; alter table DM_SELF_PROGRAM add document clob; update DM_SELF_PROGRAM set document = my_document; alter table DM_SELF_PROGRAM drop column my_document; comment on column DM_SELF_PROGRAM.document is '文件';