UTF-8 / GBK / Latin1 / Big5 编码互转，自动诊断乱码原因并给出修复建议
NLS_CHARACTERSET 查看 Oracle 字符集：SELECT * FROM NLS_DATABASE_PARAMETERS WHERE PARAMETER LIKE '%CHARACTERSET%';
NLS_NCHAR_CHARACTERSET 客户端字符集：export NLS_LANG=AMERICAN_AMERICA.AL32UTF8
SELECT * FROM nls_database_parameters WHERE parameter LIKE '%CHARACTERSET%';
character_set_server 查看 MySQL 字符集：SHOW VARIABLES LIKE 'character_set%';
character_set_client 修改表字符集：ALTER TABLE t CONVERT TO CHARACTER SET utf8mb4;
SHOW VARIABLES LIKE 'character_set%';
client_encoding 查看 PG 编码：SHOW server_encoding;
server_encoding 客户端编码：SET client_encoding TO 'UTF8';
SHOW client_encoding; SHOW server_encoding;