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???????????????????ALTER TABLE??????????????????????????????????????????????????

??????????????????????????????????permile_temp?alter table tb_test add permile_temp number(5,2)

????????????permile?????????NUMBER(5,2)???????????alter table tb_test modify permile number(5,2)

???????????permile_temp?????permile??????permile??alter table tb_test rename column permile_temp to permile;alter table tb_test drop column permile_temp;

???????????permile????????permile??????????update tb_test set permile = permile_temp;update tb_test set permile_temp = null;

????????????????????????commit;

??????????select * from tb_test;??????????????

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