MySQL Server Error:
Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (gbk_chinese_ci,COERCIBLE) for operation '='

how to change it?

first this something for the mysql forum, not the php forum, but a think you have to change your database to gbk_chinese_ci format

Basically i think the problem is that you have
latin1_swedish_ci
and
gbk_chinese_ci

Pick one and change the rest to fit with it.

Could a Mod please move this to the db forum.