create table p_key(sr_no int,name varchar2(50),primary key(sr_no));

select * from  p_key;
insert into p_key values(1,'A');

insert into p_key values(2,'B');
alter table p_key add city varchar(22);

alter table p_key drop column city;

Error starting at line : 272 in command -
alter table p_key drop column city
Error report -
ORA-12988: cannot drop column from table owned by SYS
12988. 00000 -  "cannot drop column from table owned by SYS"
*Cause:    An attempt was made to drop a column from a system table.
*Action:   This action is not allowed

它在MySQL中工作，但我想在Oracle SQL中尝试。