左连接

select tct.f_tel from    
      t_cust_consultant  as tc 
      left join
      t_project as tp
      on  tp.id = tc.f_project_id
      left join t_area as ta
      on tp.f_city_id = ta.f_code
      left join 
      t_city_tel tct
      on ta.f_pcode = tct.f_city_code

   where tc.id = 150

统计前15条数据中团费总和

select sum(b.f_tuan_fee_fu) as total_fu ,sum(b.f_tuan_fee) as tuan_fee  from
(
select f_tuan_fee_fu, f_tuan_fee from t_contract limit 0,15
 ) as b ;