删除/更新/插入0行需要ORACLE中的COMMIT吗？

Question

我刚刚运行了一个查询,说"删除了0行".在Oracle数据库中."0行"DML操作是否锁定ORACLE中的表,如果是,我是否需要COMMIT？

谢谢塔伦

Answer 1

答案是肯定的,是的.Oracle会锁定已修改的行等 - 因此,如果没有行受影响,则不会发生这种情况; 但Oracle还创建了一个subexclusive 表无论锁,其可以或可以不被修改的任何行的,并且它会释放这种锁只在COMMIT或ROLLBACK或等价物.(当然,在这种情况下,您也可以ROLLBACK- 因为没有行受到影响,效果相同).

在以下会话中轻松演示:

SQL> create table xx as
  2  select level lvl from dual connect by level <= 5;

Table created.

SQL> select * from xx;

       LVL
----------
         1
         2
         3
         4
         5

SQL> select a.object_name, b.locked_mode
  2  from   user_objects a join v$locked_object b
  3  on a.object_id = b.object_id;

no rows selected

SQL> delete from xx where lvl = 10;

0 rows deleted.

SQL> select a.object_name, b.locked_mode
  2  from   user_objects a join v$locked_object b
  3  on a.object_id = b.object_id;


OBJECT_NAME     LOCKED_MODE
--------------- -----------
XX                        3

SQL> commit;

Commit complete.

SQL> select a.object_name, b.locked_mode
  2  from   user_objects a join v$locked_object b
  3  on a.object_id = b.object_id;

no rows selected