有人问到这样的问题:如果一个用户对记录加锁，如何使其他用户看不到这条记录。
此前并未注意到这样一个用法（需要8.1.7.4.16以上的版本支持）:
[oracle@jumper oracle]$ sqlplus scott/tiger
SQL*Plus: Release 9.2.0.4.0 - Production on Fri Mar 4 11:59:46 2005
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning option
JServer Release 9.2.0.4.0 - Production
SQL> select * from dept;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
33 ORACLE beijing
35 Oracle Beijing
36 Oracle Beijing
37 Oracle Beijing
8 rows selected.
SQL> select * from dept where deptno =10 for update;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
SQL> !
[oracle@jumper oracle]$ sqlplus scott/tiger
SQL*Plus: Release 9.2.0.4.0 - Production on Fri Mar 4 12:00:14 2005
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning option
JServer Release 9.2.0.4.0 - Production
SQL> select * from dept for update skip locked;
DEPTNO DNAME LOC
---------- -------------- -------------
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
33 ORACLE beijing
35 Oracle Beijing
36 Oracle Beijing
37 Oracle Beijing
7 rows selected.
SQL>
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