ORACLE WITH CHECK OPTION×Ó¾äÏê½â
½ñÌìÒ»¸öÅóÓÑÔÚÎʹØÓÚ´´½¨ÊÓͼʱºòWITH CHECK OPTIONÊÇʲôÒâ˼£¬ÎÒµ±Ê±Ò²Ã»¶àÏ룬¾Í±È½ÏÁýͳµÄ»Ø´ðÁËһϡ£ºóÀ´×Ô¼ºÏëÁËÏ룬ºÃÏñ×Ô¼ºÒ²¼Ç²»Ì«Çå³þÁË£¬ÄÔ×ÓÀïÖ»Óиö´ó¸ÅµÄÓ¡Ïó¡£
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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.
Ê×ÏÈÀ´¿´Ò»ÏÂINSERT
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
--ÕâÀïÓÉÓÚÊÓͼÖж¨ÒåÁËwhere id=2µÄÌõ¼þ²¢ÇÒ¼ÓÓÐwith check option×Ӿ䣬ËùÒÔ²åÈëid=1µÄ¼Ç¼¾Í»á±¨´í¡£
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
Ïà¹ØÎĵµ£º
1. round(Num,n) : ËÄÉáÎåÈëÊý×ÖNum£¬±£ÁônλСÊý£¬²»Ð´NĬÈϲ»ÒªÐ¡Êý£¬ËÄÉáÎåÈëµ½ÕûÊý¸öλ
select ROUND(21.237,2) from dual;
½á¹û£º 21.24
2. trunc(Num,n) : ½ØÈ¡Êý×ÖNum£¬±£ÁônλСÊý£¬²»Ð´NĬÈÏÊÇ0£¬¼´²»ÒªÐ¡Êý
select TRUNC(21.237,2) from dual;
½á¹û£º21.2 ......
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