SQL> select * from test5; KIND LEVEL1
---------- --------------------
dds
2 ed
3 i'm a boy
3 now='23'
3 'tailong'Elapsed: 00:00:00.50
SQL> alter table test5 drop (level1);Table altered.Elapsed: 00:00:03.96
SQL> commit;Commit complete.Elapsed: 00:00:00.10
SQL> select * from test5; KIND
---------- 2
3
3
3Elapsed: 00:00:00.20
---------- --------------------
dds
2 ed
3 i'm a boy
3 now='23'
3 'tailong'Elapsed: 00:00:00.50
SQL> alter table test5 drop (level1);Table altered.Elapsed: 00:00:03.96
SQL> commit;Commit complete.Elapsed: 00:00:00.10
SQL> select * from test5; KIND
---------- 2
3
3
3Elapsed: 00:00:00.20
compatible = 8.1.0
重启动数据库,应该就可以了。