关于约束ENABLE NOVALIDATE的一个疑问

http://www.dbunix.com/?p=188

关于约束ENABLE NOVALIDATE的一个疑问

CREATE TABLE test
(id varchar2(12),
name varchar2(30) ,CONSTRAINT pk_test PRIMARY k
 
ALTER TABLE test disable CONSTRAINT pk_test

然后向表中插入两条完全一样的数据并commit

我的印象是ENABLE NOVALIDATE并不检查已经存在的数

SQL> ALTER TABLE test enable novalidate constra
ALTER TABLE test enable novalidate CONSTRAINT p
*
ERROR 位于第 1 行:
ORA-02437: 无法验证 (DBO.PK_TEST) - 违反主键

参考hrb_qiuyb文章

SQL> CREATE TABLE t(a INT,b varchar2(20));
 
TABLE created.
 
SQL> INSERT INTO t VALUES(1,'lijie');
 
1 ROW created.
 
SQL> ALTER TABLE t ADD constraints pk_t_a PRIMARY KEY(a);
 
TABLE altered.
 
SQL> SELECT constraint_name,constraint_type,STATUS FROM user_constraints
WHERE TABLE_NAME='T';
 
CONSTRAINT_NAME                C STATUS
------------------------------ - --------
PK_T_A                         P ENABLED
 
SQL> SELECT index_name,uniqueness FROM user_indexes WHERE TABLE_NAME='T';
 
INDEX_NAME                     UNIQUENES
------------------------------ ---------
PK_T_A                         UNIQUE
 
SQL> ALTER TABLE t disable constraints pk_t_a;
 
TABLE altered.
 
SQL> SELECT constraint_name,constraint_type,STATUS FROM user_constraints
WHERE TABLE_NAME='T';
 
CONSTRAINT_NAME                C STATUS
------------------------------ - --------
PK_T_A                         P DISABLED
SQL> SELECT index_name,uniqueness FROM user_indexes WHERE TABLE_NAME='T';
 
no ROWS selected
 
SQL> INSERT INTO t VALUES(1,'tina');
 
1 ROW created.
 
SQL> ALTER TABLE t enable novalidate constraints pk_t_a;
ALTER TABLE t enable novalidate constraints pk_t_a
*
ERROR at line 1:
ORA-02437: cannot validate (TAOBAO.PK_T_A) - PRIMARY KEY violated

这里问题是：primary key所依赖的唯一键索引起的.

解决方法：

SQL> CREATE TABLE t2 AS (SELECT * FROM t WHERE 1=0);
 
TABLE created.
 
SQL> CREATE INDEX ind_t2_a ON t2(a);
 
INDEX created.
 
SQL> INSERT INTO t2 VALUES(1,'lijie');
 
1 ROW created.
 
SQL> ALTER TABLE t2 ADD constraints pk_t2_a PRIMARY KEY(a);
 
TABLE altered.
 
SQL> SELECT constraint_name,constraint_type,STATUS FROM user_constraints
WHERE TABLE_NAME='T2';
 
CONSTRAINT_NAME                C STATUS
------------------------------ - --------
PK_T2_A                        P ENABLED
 
SQL> SELECT index_name,uniqueness FROM user_indexes WHERE TABLE_NAME='T2';
 
INDEX_NAME                     UNIQUENES
------------------------------ ---------
IND_T2_A                       NONUNIQUE
 
SQL> ALTER TABLE t2 disable constraints pk_t2_a;
 
TABLE altered.
 
SQL> SELECT constraint_name,constraint_type,STATUS FROM user_constraints
WHERE TABLE_NAME='T2';
 
CONSTRAINT_NAME                C STATUS
------------------------------ - --------
PK_T2_A                        P DISABLED
 
SQL> SELECT index_name,uniqueness FROM user_indexes WHERE TABLE_NAME='T2';
 
INDEX_NAME                     UNIQUENES
------------------------------ ---------
IND_T2_A                       NONUNIQUE
 
SQL> INSERT INTO t2 VALUES(1,'tina');
 
1 ROW created.
 
SQL> ALTER TABLE t2 enable validate  constraints pk_t2_a;
ALTER TABLE t2 enable validate  constraints pk_t2_a
*
ERROR at line 1:
ORA-02437: cannot validate (TAOBAO.PK_T2_A) - PRIMARY KEY violated
SQL> ALTER TABLE t2 enable novalidate constraints pk_t2_a;
 
TABLE altered.

Posted on 2008-09-11 at 下午 3:21 | Filed: 数据库 |
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