oracle exp 常见错误 EXP-00091

常见导出错误:
EXP-00091: Exporting questionable statistics.
Export terminated successfully with warnings.

语言环境问题
select value from nls_database_parameters t where t.parameter='NLS_CHARACTERSET';
VALUE
--------------------------------------------------------------------------------
ZHS16GBK

设定语言环境
export NLS_LANG='SIMPLIFIED CHINESE_CHINA.ZHS16GBK'