sql每一个join都要加on

例如：

select a.id,a.date from CMS_Data a
join CMS_Column_Rel_Product b on a.colproID=b.id
join CMS_Menu c on b.menu_num=c.menu_num
left join CMS_Address d on b.area_num=d.id
where b.menu_num=1 and a.Disabled=0