将varchar修改为clob的方法

一切都要先问清楚了再做，事实是不需要这么去做的，大字段在计算的时候不需要，所以大字段都可以删除掉，只留统计信息就可以了

1.alter table patent_analysis.sys_patent_info add(tmp clob)；2，ALTER TABLE sys_patent_info NOLOGGIdeclare i integer;BEGIN  i := 0;  for crCompany in (select t.code, t.SOVEREIGNTY from patent_analysis.sys_patent_info t) loopupdate /*+ PARALLEL */ sys_patent_info set tmp = crCompany.SOVEREIGNTY where code= crCompany.code ;    i := i+1;    if mod(i,100) = 0 then      commit;    end if;  end LOOP;  commit;end;

3，alter table patent_analysis.sys_patent_info rename column SOVEREIGNTY to SOVEREIGNTY_bak;
4,alter table patent_analysis.sys_patent_info rename column tmp to SOVEREIGNTY;
5,alter table patent_analysis.sys_patent_info drop (SOVEREIGNTY);
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