select MIN(SUBSTRING(wr_reply, 1, 1)) as reply from where wr_num = '' and SUBSTRING(wr_reply, 1, 1) <> ''

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 'where wr_num = '' and SUBSTRING(wr_reply, 1, 1) <> ''' at line 1

error file : /gb/bbs/write.php