select a.man_id,man_name,d.sex_name,zw_name,c.money 
 from man as a  
      left join zw as b on a.zw_id=b.zw_id  
      left join zw as c on a.man_id=c.man_id   -- 同时关联zw字段，通过表别名区别开
      left join xb as d on c.sex_id=d.sex_id