ora-01440:column to be modified must be empty to decrease precision or scale解决
ora-01440:column to be modified must be empty to decrease precision or scale解决
问题缘由：
客户要求某个字段支持小数点，数据库一开始设计的时候只支持整数，在通过alert语句修改类型，出现了ora-001440的错误，
解决办法
step1：备份原来的表，
create table WF_TEACHER_REMUNERATION_BAK
as select * from WF_TEACHER_REMUNERATION;
step2：删除原来表的数据
delete from
WF_TEACHER_REMUNERATION
;
step3：修改精度
ALTER TABLE "DHOFFICE"."WF_TEACHER_REMUNERATION"
MODIFY ( "CLASS_TIME" NUMBER(10,2) ) ;
step4：恢复数据
insert into
WF_TEACHER_REMUNERATION
select * from
WF_TEACHER_REMUNERATION_BAK
；
step by step ，打完毕，收工！
