导入数据时报错以下错误，这是因为原来的数据库是GBK的，每个汉字两个字节，但新数据库是UTF-8的，每个汉字是三个字节，导致超过长度了。
ORA-12899: value too large for column (actual: 27, maximum: 20)
解决：
开始-->运行-->cmd,之后输入:"sqlplus /nolog"，进入"SQL>"的提示，按照下面给出的命令依次执行就可以了：
SQL>connect username/password as SYSDBA;
SQL>SHUTDOWN IMMEDIATE;
SQL>STARTUP MOUNT;
SQL>ALTER SYSTEM ENABLE RESTRICTED SESSION;
SQL>ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;
SQL>ALTER SYSTEM SET AQ_TM_PROCESSES=0;
SQL>ALTER DATABASE OPEN;
SQL> ALTER DATABASE CHARACTER SET ZHS16GBK ;
ALTER DATABASE CHARACTER SET ZHS16GBK;
*ERROR at line 1:
ORA-12712: new character set must be a superset of old character set
报字符集不兼容，此时下INTERNAL_USE指令不对字符集超集进行检查：
SQL>ALTER DATABASE CHARACTER SET INTERNAL_USE ZHS16GBK;
SQL>SHUTDOWN IMMEDIATE;
SQL>STARTUP;