发生了一个数据库错误

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'GROUP BY `cityid` ORDER BY `citynumber` DESC, `cityname` ASC' at line 4

SELECT `cityid`, `cityname` FROM (`chi_course_index`) WHERE `state` = 1 AND schoolstate = 1 AND cooperation = 1 AND education = 0 AND opentime > 1672502400 AND opentime > 1735660800 AND opentime < 1753977600 AND tuition >= null AND tuition <= GROUP BY `cityid` ORDER BY `citynumber` DESC, `cityname` ASC

Filename: controllers/search.php

Line Number: 650