Ora-01440: column to be modified must be empty to decrease pr

Ora-01440: column to be modified must be empty to decrease precision or scale solve problem reason: the customer asked a field to support decimal point, the database at the beginning of the design only supports integer, in the alert statement to modify the type, a ora-001440 error occurs, solution step1: Back up the original table, create table WF_TEACHER_REMUNERATION_BAK as select * from WF_TEACHER_REMUNERATION; step2: delete the data in the original TABLE: delete from WF_TEACHER_REMUNERATION; Step 3: Modify the precision of alter table "DHOFFICE ". "WF_TEACHER_REMUNERATION" MODIFY ("CLASS_TIME" NUMBER (10, 2); step 4: recover data insert into WF_TEACHER_REMUNERATION select * from WF_TEACHER_REMUNERATION_BAK; step by step. After the operation is completed, close the job!