select max(j_camera.price) as camera,max(j_note.price) as note,max(j_phone.price) as phone,max(j_pad.price) as pad,max(j_earphone.price) as earphone,max(j_wear.price) as wear
from j_camera,j_note,j_phone,j_pad,j_earphone,j_wear
where j_camera.ptid=j_note.ptid=j_phone.ptid=j_pad.ptid=j_earphone.ptid=j_wear.ptid
数据库有点大，数据库运行不起
把条件对应写清楚 and 连接 试试！或者 分开表查询 然后 union