SQL> create table temo(a VARCHAR2(10),b NVARCHAR2(20));Table created
SQL> insert into temo values('1',null);1 row insertedSQL> update temo set a=b;update temo set a=bORA-12704: 字符集不匹配
SQL> select * from temo;A B
---------- --------------------
1
SQL> update temo set a=to_char(b);1 row updatedSQL> select * from temo; A B
---------- --------------------
SQL> insert into temo values('1',null);1 row insertedSQL> update temo set a=b;update temo set a=bORA-12704: 字符集不匹配
SQL> select * from temo;A B
---------- --------------------
1
SQL> update temo set a=to_char(b);1 row updatedSQL> select * from temo; A B
---------- --------------------
解决方案 »
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