oracle – 要修改的列不是标识列

我创建了一个包含列S_ROLL NUMBER(3)NOT NULL的表现在我想将此列作为标识列.

我用过这个命令

alter table students
modify
(
S_ROLL NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY
);

然后我收到了这个错误.

S_ROLL NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY
*
ERROR at line 4:
ORA-30673: column to be modified is not an identity column

您只是因为现在不支持将现有列修改为IDENTITY列而收到此错误.