oracle 11g win7_64位 乱码,该如何处理

oracle 11g win7_64位 乱码
执行带中文的sql语句,sql语句中文自动变成乱码,手动插入也会这样,怎么会事啊!
show parameter nls;结果
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
nls_calendar                         string      
nls_comp                             string      BINARY
nls_currency                         string      
nls_date_format                      string      
nls_date_language                    string      
nls_dual_currency                    string      
nls_iso_currency                     string      
nls_language                         string      AMERICAN
nls_length_semantics                 string      BYTE
nls_nchar_conv_excp                  string      FALSE
nls_numeric_characters               string      
nls_sort                             string      
nls_territory                        string      AMERICA
nls_time_format                      string      
nls_time_tz_format                   string      
nls_timestamp_format                 string      
nls_timestamp_tz_format              string      
[解决办法]
字符集问题，看一下你的服务器字符集：

select * from nls_database_parameters where parameter='NLS_CHARACTERSET';