ORACLE WITH CHECK OPTION子句详解

今天一个朋友在问关于创建视图时候WITH CHECK OPTION是什么意思，我当时也没多想，就比较笼统的回答了一下。后来自己想了想，好像自己也记不太清楚了，脑子里只有个大概的印象。
好了话不多说，下面还是通过实验来看一下吧。
C:\Documents and Settings\Admin>sqlplus /nolog
SQL*Plus: Release 10.2.0.1.0 - Production on Sat Nov 14 20:22:13 2009
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
SQL> show user
USER is ""
SQL> conn scott/tiger
Connected.
SQL> drop table t1;
Table dropped.
SQL> create table t1(id number,name varchar2(20));
Table created.
SQL> insert into t1 values(1,'wh')
  2  ;
1 row created.
SQL> insert into t1 values(2,'wp');
1 row created.
SQL> insert into t1 values(3,'wr');
1 row created.
SQL> commit;
Commit complete.
SQL> select * from t1;
        ID NAME
---------- --------------------
         1 wh
         2 wp
         3 wr
SQL> create view v_t1
  2  as
  3  select * from t1
  4  where id=2
  5  with check option;
View created.
首先来看一下INSERT
SQL> insert into v_t1 values(1,'haha');
insert into v_t1 values(1,'haha')
            *
ERROR at line 1:
ORA-01402: view WITH CHECK OPTION where-clause violation
--这里由于视图中定义了where id=2的条件并且加有with check option子句，所以插入id=1的记录就会报错。
SQL> insert into v_t1 values(2,'haha');
1 row created.
SQL> commit;
Commit complete.
SQL> select * from t1;
        ID NAME
---------- --------------------
         1 wh
         2 wp
         3 wr
         2 haha