这样写是OK的：
select * from bind_history limit 10;
select id, passport_id, person_id, create_time, cast(is_bind AS char(1)) from bind_history_0000;
select id, passport_id, person_id, create_time, cast(is_bind AS char) from bind_history;
select id, passport_id, person_id, create_time, convert(is_bind,char(1)) from account.passport_bind_history limit 10;
select id, passport_id, person_id, create_time, convert(is_bind,char) from account.passport_bind_history limit 10;
这样写不行：
select id, passport_id, person_id, create_time, cast(is_bind AS char(1)) from bind_history;
不建议使用
