SQL> create table aaa (a number(9));Table created.Elapsed: 00:00:00.32
SQL> insert into aaa values(999);1 row created.Elapsed: 00:00:00.03
SQL> commit;Commit complete.Elapsed: 00:00:00.00
SQL> alter table aaa add b varchar2(5);Table altered.Elapsed: 00:00:00.17
SQL> update aaa set a=b;1 row updated.Elapsed: 00:00:00.02
SQL> commit;Commit complete.Elapsed: 00:00:00.03
SQL> alter table aaa drop column a;Table altered.Elapsed: 00:00:00.52
SQL> alter table aaa rename column b to a;Table altered.Elapsed: 00:00:00.04
SQL>
SQL> insert into aaa values(999);1 row created.Elapsed: 00:00:00.03
SQL> commit;Commit complete.Elapsed: 00:00:00.00
SQL> alter table aaa add b varchar2(5);Table altered.Elapsed: 00:00:00.17
SQL> update aaa set a=b;1 row updated.Elapsed: 00:00:00.02
SQL> commit;Commit complete.Elapsed: 00:00:00.03
SQL> alter table aaa drop column a;Table altered.Elapsed: 00:00:00.52
SQL> alter table aaa rename column b to a;Table altered.Elapsed: 00:00:00.04
SQL>
解决方案 »
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