ORA-01779: 无法修改与非键值保存表对应的列
(2014-05-06 11:43:55)
标签:
updateviweora-01779 |
分类: SQL |
对数据库检查没有主键的表检查,请参看http://blog.sina.com.cn/s/blog_b43f755b0101gkyb.html
create table test1
(
id number,
gender varchar2(10)
);
insert into test1 values(1,'男');
insert into test1 values(2,'女');
insert into test1 values(3,'女');
insert into test1 values(4,'女');
表test2
create table test2
(
id number,
gender varchar2(10)
);
insert into test2 values(2,'男');
insert into test2 values(3,'男');
insert into test2 values(5,'女');
现在情况如下,test1与test2中ID相同的,我想用test2中的gender更新test1中的gender,使用下列语句
UPDATE
(
SELECT A.ID AI,A.GENDER AG,B.ID BI,B.GENDER BG FROM TEST1 A,TEST2 B
WHERE
A.ID = B.ID
)
SET AG = BG;
ERROR AT LINE 6:
ORA-01779: CANNOT MODIFY A COLUMN WHICH MAPS TO A NON KEY-PRESERVED
TABLE
这个错误产生的原因是子查询的结果中,用来更新test1的test2表id不唯一,导致被更新对象test1中的一行可能要对应test2中的很多行,这样oracle就不知道该怎么更新
解决办法
1.给test2加上一个主键.
SQL>
ALTER TABLE TEST2 ADD PRIMARY KEY(ID);
TABLE ALTERED.
SQL> UPDATE
2 (
3 SELECT A.ID AI,A.GENDER AG,B.ID BI,B.GENDER BG FROM TEST1 A,TEST2
B WHERE
4 A.ID = B.ID
5 )
6 SET AG = BG;
2 ROWS UPDATED.
SQL>SELECT * FROM TEST1;
SQL> ALTER TABLE TEST2 DROP PRIMARY KEY;
TABLE ALTERED.
2.给test2加上一个唯一索引
SQL> CREATE UNIQUE INDEX IDX_TEST2 ON TEST2(ID);
INDEX CREATED.
SQL> UPDATE
2 (
3 SELECT A.ID AI,A.GENDER AG,B.ID BI,B.GENDER BG FROM TEST1 A,TEST2
B WHERE
4 A.ID = B.ID
5 )
6 SET AG = BG;
2 ROWS UPDATED.
SQL> DROP INDEX IDX_TEST2;
INDEX DROPPED.
3.使用BYPASS_UJVC强制执行,BYPASS_UJVC可以跳过ORACLE的键检查.
SQL> UPDATE
2 (
3 SELECT A.ID AI,A.GENDER AG,B.ID BI,B.GENDER BG FROM TEST1 A,TEST2
B WHERE
4 A.ID = B.ID
5 )
6 SET AG = BG;
2 rows updated.
虽然这样可以执行,但是test2中存在不唯一的数据,所以test1可能被更新多次.

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