alter table COLUMNS_V2 modify column COMMENT varchar(256) character set utf8; //修改字段注釋字符集
alter table TABLE_PARAMS modify column PARAM_VALUE varchar(4000) character set utf8; //修改表注釋字符集
alter table PARTITION_KEYS modify column PKEY_COMMENT varchar(4000) character set utf8; //修改分區注釋字符集
alter table TABLE_PARAMS change PARAM_VALUE PARAM_VALUE VARCHAR(4000) charset utf8 COLLATE utf8_bin NULL; //修改表說明注釋字符集
